[Gitar] Cleaning up stale feature flag: stripClientHeadersOn304 with value true (#6868)

<details>
  <summary>Feature Flag Cleanup</summary>

  | Stale Flag |  Value  |
  | ---------- | ------- |
  |   stripClientHeadersOn304   | true |

  </details>

  <details>
  <summary>Trigger</summary>

  https://github.com/Unleash/unleash/issues/6559#issuecomment-2058848984

  </details>

  <details>
  <summary>Bot Commands</summary>

`@gitar-bot cleanup stale_flag=value` will cleanup a stale feature flag.
Replace `stale_flag` with the name of the stale feature flag and `value`
with either `true` or `false`.

  </details>

---------

Co-authored-by: Gitar Bot <noreply@gitar.co>

src/lib/__snapshots__/create-config.test.ts.snap

@@ -144,7 +144,6 @@ exports[`should create default config 1`] = `
       "showInactiveUsers": false,
       "signals": false,
       "strictSchemaValidation": false,
-      "stripClientHeadersOn304": false,
       "useMemoizedActiveTokens": false,
       "userAccessUIEnabled": false,
       "variantDependencies": false,

src/lib/features/client-feature-toggles/client-feature-toggle.controller.ts

@@ -241,11 +241,7 @@ export default class FeatureController extends Controller {
 
         if (etag === userVersion) {
             res.status(304);
-            if (this.flagResolver.isEnabled('stripClientHeadersOn304')) {
+            res.getHeaderNames().forEach((header) => res.removeHeader(header));
-                res.getHeaderNames().forEach((header) =>
-                    res.removeHeader(header),
-                );
-            }
             res.end();
             return;
         } else {

src/lib/features/metrics/instance/metrics.ts

@@ -120,11 +120,9 @@ export default class ClientMetricsController extends Controller {
                 );
 
                 await this.metricsV2.registerClientMetrics(data, clientIp);
-                if (this.flagResolver.isEnabled('stripClientHeadersOn304')) {
+                res.getHeaderNames().forEach((header) =>
-                    res.getHeaderNames().forEach((header) =>
+                    res.removeHeader(header),
-                        res.removeHeader(header),
+                );
-                    );
-                }
                 res.status(202).end();
             } catch (e) {
                 res.status(400).end();

src/lib/types/experimental.ts

@@ -25,7 +25,6 @@ export type IFlagKey =
     | 'advancedPlayground'
     | 'filterInvalidClientMetrics'
     | 'disableMetrics'
-    | 'stripClientHeadersOn304'
     | 'stripHeadersOnAPI'
     | 'signals'
     | 'automatedActions'
@@ -133,11 +132,6 @@ const flags: IFlags = {
         process.env.UNLEASH_EXPERIMENTAL_DISABLE_METRICS,
         false,
     ),
-    stripClientHeadersOn304: parseEnvVarBoolean(
-        process.env
-            .UNLEASH_EXPERIMENTAL_DETECT_SEGMENT_USAGE_IN_CHANGE_REQUESTS,
-        false,
-    ),
     signals: parseEnvVarBoolean(
         process.env.UNLEASH_EXPERIMENTAL_SIGNALS,
         false,

src/server-dev.ts

@@ -40,7 +40,6 @@ process.nextTick(async () => {
                         embedProxyFrontend: true,
                         anonymiseEventLog: false,
                         responseTimeWithAppNameKillSwitch: false,
-                        stripClientHeadersOn304: true,
                         stripHeadersOnAPI: true,
                         celebrateUnleash: true,
                         featureSearchFeedbackPosting: true,