chore(cli): remove unreachable v1 compat in stack selection (aws#32620)

### Reason for this change

Removing dead code. The version number of the `CLI is never < 2` in release and thus this code cannot be reached.
This allowed to remove the env variable hack that enabled test scenarios to use v2 behavior.

### Description of changes

Remove the unreachable if statement and then optimize code.
Also includes some minor reformatting of method parameters.

### Describe any new or updated permissions being added

n/a

### Description of how you validated changes

Test pipeline.

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/aws-cdk/lib/api/cxapp/cloud-assembly.ts

@@ -4,7 +4,6 @@ import { minimatch } from 'minimatch';
 import * as semver from 'semver';
 import { error, print, warning } from '../../logging';
 import { flatten } from '../../util';
-import { versionNumber } from '../../version';
 
 export enum DefaultSelection {
   /**
@@ -122,43 +121,35 @@ export class CloudAssembly {
     }
   }
 
-  private selectTopLevelStacks(stacks: cxapi.CloudFormationStackArtifact[],
+  private selectTopLevelStacks(
+    stacks: cxapi.CloudFormationStackArtifact[],
     topLevelStacks: cxapi.CloudFormationStackArtifact[],
-    extend: ExtendedStackSelection = ExtendedStackSelection.None): StackCollection {
+    extend: ExtendedStackSelection = ExtendedStackSelection.None,
+  ): StackCollection {
     if (topLevelStacks.length > 0) {
       return this.extendStacks(topLevelStacks, stacks, extend);
     } else {
       throw new Error('No stack found in the main cloud assembly. Use "list" to print manifest');
     }
   }
 
-  private selectMatchingStacks(stacks: cxapi.CloudFormationStackArtifact[],
+  private selectMatchingStacks(
+    stacks: cxapi.CloudFormationStackArtifact[],
     patterns: string[],
-    extend: ExtendedStackSelection = ExtendedStackSelection.None): StackCollection {
-
-    // cli tests use this to ensure tests do not depend on legacy behavior
-    // (otherwise they will fail in v2)
-    const disableLegacy = process.env.CXAPI_DISABLE_SELECT_BY_ID === '1';
-
-    const matchingPattern = (pattern: string) => (stack: cxapi.CloudFormationStackArtifact) => {
-      if (minimatch(stack.hierarchicalId, pattern)) {
-        return true;
-      } else if (!disableLegacy && stack.id === pattern && semver.major(versionNumber()) < 2) {
-        warning('Selecting stack by identifier "%s". This identifier is deprecated and will be removed in v2. Please use "%s" instead.', chalk.bold(stack.id), chalk.bold(stack.hierarchicalId));
-        warning('Run "cdk ls" to see a list of all stack identifiers');
-        return true;
-      }
-      return false;
-    };
+    extend: ExtendedStackSelection = ExtendedStackSelection.None,
+  ): StackCollection {
 
+    const matchingPattern = (pattern: string) => (stack: cxapi.CloudFormationStackArtifact) => minimatch(stack.hierarchicalId, pattern);
     const matchedStacks = flatten(patterns.map(pattern => stacks.filter(matchingPattern(pattern))));
 
     return this.extendStacks(matchedStacks, stacks, extend);
   }
 
-  private selectDefaultStacks(stacks: cxapi.CloudFormationStackArtifact[],
+  private selectDefaultStacks(
+    stacks: cxapi.CloudFormationStackArtifact[],
     topLevelStacks: cxapi.CloudFormationStackArtifact[],
-    defaultSelection: DefaultSelection) {
+    defaultSelection: DefaultSelection,
+  ) {
     switch (defaultSelection) {
       case DefaultSelection.MainAssembly:
         return new StackCollection(this, topLevelStacks);
@@ -178,9 +169,11 @@ export class CloudAssembly {
     }
   }
 
-  private extendStacks(matched: cxapi.CloudFormationStackArtifact[],
+  private extendStacks(
+    matched: cxapi.CloudFormationStackArtifact[],
     all: cxapi.CloudFormationStackArtifact[],
-    extend: ExtendedStackSelection = ExtendedStackSelection.None) {
+    extend: ExtendedStackSelection = ExtendedStackSelection.None,
+  ) {
     const allStacks = new Map<string, cxapi.CloudFormationStackArtifact>();
     for (const stack of all) {
       allStacks.set(stack.hierarchicalId, stack);

packages/aws-cdk/test/api/cloud-assembly.test.ts

@@ -4,9 +4,6 @@ import { DefaultSelection } from '../../lib/api/cxapp/cloud-assembly';
 import { MockCloudExecutable } from '../util';
 import { cliAssemblyWithForcedVersion } from './assembly-versions';
 
-// behave like v2
-process.env.CXAPI_DISABLE_SELECT_BY_ID = '1';
-
 test('do not throw when selecting stack without errors', async () => {
   // GIVEN
   const cxasm = await testCloudAssembly();

packages/aws-cdk/test/cdk-toolkit.test.ts

@@ -95,8 +95,6 @@ import { flatten } from '../lib/util';
 
 markTesting();
 
-process.env.CXAPI_DISABLE_SELECT_BY_ID = '1';
-
 const defaultBootstrapSource: BootstrapSource = { source: 'default' };
 const bootstrapEnvironmentMock = jest.spyOn(Bootstrapper.prototype, 'bootstrapEnvironment');
 let cloudExecutable: MockCloudExecutable;