chore(lint): Fix suppressed ESLint errors in polling-controller package (#7435)

## Explanation

This fixes all suppressed ESLint errors in the `polling-controller`
package.

## References

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* Fixes #12345
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Closes #7383.

## Checklist

- [ ] I've updated the test suite for new or updated code as appropriate
- [ ] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [ ] I've communicated my changes to consumers by [updating changelogs
for packages I've
changed](https://github.com/MetaMask/core/tree/main/docs/contributing.md#updating-changelogs)
- [ ] I've introduced [breaking
changes](https://github.com/MetaMask/core/tree/main/docs/breaking-changes.md)
in this PR and have prepared draft pull requests for clients and
consumer packages to resolve them

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Adds explicit return types and targeted ESLint-disable annotations to
polling controller mixins and tests, removing related suppressions.
> 
> - **Polling Controller**:
> - **BlockTrackerPollingController**
(`packages/polling-controller/src/BlockTrackerPollingController.ts`):
> - Add explicit return types to `_startPolling` and
`_stopPollingByPollingTokenSetId`.
> - Document/annotate mixin factory and exported helpers with ESLint
disables for inferred return types.
> - **StaticIntervalPollingController**
(`packages/polling-controller/src/StaticIntervalPollingController.ts`):
> - Add explicit return types to `setIntervalLength`,
`getIntervalLength`, `_startPolling`, and
`_stopPollingByPollingTokenSetId`.
> - Document/annotate mixin factory and exported helpers with ESLint
disables for inferred return types.
> - **Tests**
(`packages/polling-controller/src/StaticIntervalPollingController.test.ts`):
> - Rename callback param `err` to `error` in deferred promise handlers.
> - **ESLint Suppressions**:
> - Remove suppressions for updated polling-controller files in
`eslint-suppressions.json`.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
91d0c5a. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: Mrtenz

eslint-suppressions.json

@@ -2652,27 +2652,6 @@
       "count": 1
     }
   },
-  "packages/polling-controller/src/BlockTrackerPollingController.ts": {
-    "@typescript-eslint/explicit-function-return-type": {
-      "count": 5
-    },
-    "@typescript-eslint/naming-convention": {
-      "count": 1
-    }
-  },
-  "packages/polling-controller/src/StaticIntervalPollingController.test.ts": {
-    "id-denylist": {
-      "count": 1
-    }
-  },
-  "packages/polling-controller/src/StaticIntervalPollingController.ts": {
-    "@typescript-eslint/explicit-function-return-type": {
-      "count": 7
-    },
-    "@typescript-eslint/naming-convention": {
-      "count": 1
-    }
-  },
   "packages/profile-sync-controller/src/controllers/authentication/AuthenticationController.test.ts": {
     "@typescript-eslint/explicit-function-return-type": {
       "count": 5

packages/polling-controller/src/BlockTrackerPollingController.ts

@@ -26,6 +26,9 @@ export type BlockTrackerPollingInput = {
  * @param Base - The base class to mix onto.
  * @returns The composed class.
  */
+// This is a function that's used as class, and the return type is inferred from
+// the class defined inside the function scope, so this can't be easily typed.
+// eslint-disable-next-line @typescript-eslint/explicit-function-return-type, @typescript-eslint/naming-convention
 function BlockTrackerPollingControllerMixin<
   TBase extends Constructor,
   PollingInput extends BlockTrackerPollingInput,
@@ -40,7 +43,7 @@ function BlockTrackerPollingControllerMixin<
       networkClientId: NetworkClientId,
     ): NetworkClient | undefined;
 
-    _startPolling(input: PollingInput) {
+    _startPolling(input: PollingInput): void {
       const key = getKey(input);
 
       if (this.#activeListeners[key]) {
@@ -61,7 +64,7 @@ function BlockTrackerPollingControllerMixin<
       }
     }
 
-    _stopPollingByPollingTokenSetId(key: PollingTokenSetId) {
+    _stopPollingByPollingTokenSetId(key: PollingTokenSetId): void {
       const { networkClientId } = JSON.parse(key);
       const networkClient = this._getNetworkClientById(
         networkClientId as NetworkClientId,
@@ -86,10 +89,16 @@ class Empty {}
 
 export const BlockTrackerPollingControllerOnly = <
   PollingInput extends BlockTrackerPollingInput,
+  // The return type is inferred from the class defined inside the function
+  // scope, so this can't be easily typed.
+  // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
 >() => BlockTrackerPollingControllerMixin<typeof Empty, PollingInput>(Empty);
 
 export const BlockTrackerPollingController = <
   PollingInput extends BlockTrackerPollingInput,
+  // The return type is inferred from the class defined inside the function
+  // scope, so this can't be easily typed.
+  // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
 >() =>
   BlockTrackerPollingControllerMixin<typeof BaseController, PollingInput>(
     BaseController,

packages/polling-controller/src/StaticIntervalPollingController.test.ts

@@ -25,7 +25,7 @@ class ChildBlockTrackerPollingController extends StaticIntervalPollingController
   any
 > {
   executePollPromises: {
-    reject: (err: unknown) => void;
+    reject: (error: unknown) => void;
     resolve: () => void;
   }[] = [];
 

packages/polling-controller/src/StaticIntervalPollingController.ts

@@ -18,6 +18,9 @@ import type {
  * @param Base - The base class to mix onto.
  * @returns The composed class.
  */
+// This is a function that's used as class, and the return type is inferred from
+// the class defined inside the function scope, so this can't be easily typed.
+// eslint-disable-next-line @typescript-eslint/explicit-function-return-type, @typescript-eslint/naming-convention
 function StaticIntervalPollingControllerMixin<
   TBase extends Constructor,
   PollingInput extends Json,
@@ -30,15 +33,15 @@ function StaticIntervalPollingControllerMixin<
 
     #intervalLength: number | undefined = 1000;
 
-    setIntervalLength(intervalLength: number) {
+    setIntervalLength(intervalLength: number): void {
       this.#intervalLength = intervalLength;
     }
 
-    getIntervalLength() {
+    getIntervalLength(): number | undefined {
       return this.#intervalLength;
     }
 
-    _startPolling(input: PollingInput) {
+    _startPolling(input: PollingInput): void {
       if (!this.#intervalLength) {
         throw new Error('intervalLength must be defined and greater than 0');
       }
@@ -65,7 +68,7 @@ function StaticIntervalPollingControllerMixin<
       ));
     }
 
-    _stopPollingByPollingTokenSetId(key: PollingTokenSetId) {
+    _stopPollingByPollingTokenSetId(key: PollingTokenSetId): void {
       const intervalId = this.#intervalIds[key];
       if (intervalId) {
         clearTimeout(intervalId);
@@ -81,8 +84,14 @@ class Empty {}
 
 export const StaticIntervalPollingControllerOnly = <
   PollingInput extends Json,
+  // The return type is inferred from the class defined inside the function
+  // scope, so this can't be easily typed.
+  // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
 >() => StaticIntervalPollingControllerMixin<typeof Empty, PollingInput>(Empty);
 
+// The return type is inferred from the class defined inside the function
+// scope, so this can't be easily typed.
+// eslint-disable-next-line @typescript-eslint/explicit-function-return-type
 export const StaticIntervalPollingController = <PollingInput extends Json>() =>
   StaticIntervalPollingControllerMixin<typeof BaseController, PollingInput>(
     BaseController,