chore: filter out milestone strategies in features_view (#8883)

https://linear.app/unleash/issue/2-3033/filter-out-release-plan-milestone-strategies-from-admin-feature

Filters out milestone strategies from our `features_view`.

This felt like the most elegant way to address this, since it seems we
only rely on this view to fetch the feature strategies in the admin UI.


### No more milestone strategies showing up on our UI when we have a
running milestone


![image](https://github.com/user-attachments/assets/02bac5a5-7ddb-4bde-b487-8b6bca0923b5)

### However they're still part of the client features response

```json
{
	"name": "r-plan",
	"type": "release",
	"enabled": false,
	"project": "default",
	"stale": false,
	"strategies": [
		{
			"name": "flexibleRollout",
			"constraints": [
				{
					"values": [
						"Portugal"
					],
					"inverted": false,
					"operator": "IN",
					"contextName": "country",
					"caseInsensitive": false
				},
				{
					"values": [
						"Portugal",
						"Norway"
					],
					"inverted": false,
					"operator": "IN",
					"contextName": "country",
					"caseInsensitive": false
				}
			],
			"parameters": {
				"groupId": "newOverview",
				"rollout": "100",
				"stickiness": "default"
			},
			"variants": [
				{
					"name": "A",
					"weight": 500,
					"stickiness": "default",
					"weightType": "variable"
				},
				{
					"name": "B",
					"weight": 500,
					"stickiness": "default",
					"weightType": "variable"
				}
			]
		},
		{
			"name": "flexibleRollout",
			"constraints": [],
			"parameters": {
				"groupId": "much_feature",
				"rollout": "25",
				"stickiness": "default"
			},
			"variants": []
		},
		{
			"name": "flexibleRollout",
			"constraints": [],
			"parameters": {
				"groupId": "r-plan",
				"rollout": "100",
				"stickiness": "default"
			},
			"variants": []
		}
	],
	"variants": [],
	"description": null,
	"impressionData": false
},
```

src/lib/features/feature-toggle/feature-toggle-strategies-store.ts

@@ -538,9 +538,6 @@ class FeatureStrategiesStore implements IFeatureStrategiesStore {
                 e.strategies = e.strategies.sort(
                     (a, b) => a.sortOrder - b.sortOrder,
                 );
-                if (e.strategies && e.strategies.length === 0) {
-                    e.enabled = false;
-                }
                 return e;
             });
 

src/migrations/20241128152334-features-view-filter-out-milestone-strategies.js

@@ -0,0 +1,103 @@
+'use strict';
+
+exports.up = function (db, callback) {
+    db.runSql(
+        `
+          DROP VIEW features_view;
+
+          CREATE VIEW features_view AS
+          SELECT
+              features.name as name,
+              features.description as description,
+              features.type as type,
+              features.project as project,
+              features.stale as stale,
+              features.impression_data as impression_data,
+              features.created_at as created_at,
+              features.archived_at as archived_at,
+              features.last_seen_at as last_seen_at,
+              feature_environments.last_seen_at as env_last_seen_at,
+              feature_environments.enabled as enabled,
+              feature_environments.environment as environment,
+              feature_environments.variants as variants,
+              environments.name as environment_name,
+              environments.type as environment_type,
+              environments.sort_order as environment_sort_order,
+              feature_strategies.id as strategy_id,
+              feature_strategies.strategy_name as strategy_name,
+              feature_strategies.parameters as parameters,
+              feature_strategies.constraints as constraints,
+              feature_strategies.sort_order as sort_order,
+              fss.segment_id as segments,
+              feature_strategies.title as strategy_title,
+              feature_strategies.disabled as strategy_disabled,
+              feature_strategies.variants as strategy_variants,
+              users.id as user_id,
+              users.name as user_name,
+              users.username as user_username,
+              users.email as user_email
+          FROM
+              features
+                  LEFT JOIN feature_environments ON feature_environments.feature_name = features.name
+                  LEFT JOIN (
+                      SELECT *
+                      FROM feature_strategies
+                      WHERE milestone_id IS NULL
+                  ) AS feature_strategies ON feature_strategies.feature_name = feature_environments.feature_name
+                  and feature_strategies.environment = feature_environments.environment
+                  LEFT JOIN environments ON feature_environments.environment = environments.name
+                  LEFT JOIN feature_strategy_segment as fss ON fss.feature_strategy_id = feature_strategies.id
+                  LEFT JOIN users ON users.id = features.created_by_user_id;
+        `,
+        callback,
+    );
+};
+
+exports.down = function (db, callback) {
+    db.runSql(
+        `
+          DROP VIEW features_view;
+
+          CREATE VIEW features_view AS
+          SELECT
+              features.name as name,
+              features.description as description,
+              features.type as type,
+              features.project as project,
+              features.stale as stale,
+              features.impression_data as impression_data,
+              features.created_at as created_at,
+              features.archived_at as archived_at,
+              features.last_seen_at as last_seen_at,
+              feature_environments.last_seen_at as env_last_seen_at,
+              feature_environments.enabled as enabled,
+              feature_environments.environment as environment,
+              feature_environments.variants as variants,
+              environments.name as environment_name,
+              environments.type as environment_type,
+              environments.sort_order as environment_sort_order,
+              feature_strategies.id as strategy_id,
+              feature_strategies.strategy_name as strategy_name,
+              feature_strategies.parameters as parameters,
+              feature_strategies.constraints as constraints,
+              feature_strategies.sort_order as sort_order,
+              fss.segment_id as segments,
+              feature_strategies.title as strategy_title,
+              feature_strategies.disabled as strategy_disabled,
+              feature_strategies.variants as strategy_variants,
+              users.id as user_id,
+              users.name as user_name,
+              users.username as user_username,
+              users.email as user_email
+          FROM
+              features
+                  LEFT JOIN feature_environments ON feature_environments.feature_name = features.name
+                  LEFT JOIN feature_strategies ON feature_strategies.feature_name = feature_environments.feature_name
+                  and feature_strategies.environment = feature_environments.environment
+                  LEFT JOIN environments ON feature_environments.environment = environments.name
+                  LEFT JOIN feature_strategy_segment as fss ON fss.feature_strategy_id = feature_strategies.id
+                  LEFT JOIN users ON users.id = features.created_by_user_id;
+        `,
+        callback,
+    );
+};