Do not notify the FE on experiment activation (#3450)

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Task/Issue URL:
https://app.asana.com/0/1204099484721401/1208531438887018/f

**Description**:
- Mitigates Frontend issue causing DuckPlayer to be stuck in Youtube
Mode

DuckDuckGo/DuckPlayer/DuckPlayerNavigationHandler.swift

@@ -228,15 +228,15 @@ final class DuckPlayerNavigationHandler {
             // Enroll user if not enrolled
             if !experiment.isEnrolled {
                 experiment.assignUserToCohort()
-            }
-
-            // DuckPlayer is disabled before user enrolls,
-            // So trigger a settings change notification
-            // to let the FE know about the 'actual' setting
-            // and update Experiment value
-            if experiment.isExperimentCohort {
-                duckPlayer.settings.triggerNotification()
-                experiment.duckPlayerMode = duckPlayer.settings.mode
+                
+                // DuckPlayer is disabled before user enrolls,
+                // So trigger a settings change notification
+                // to let the FE know about the 'actual' setting
+                // and update Experiment value
+                if experiment.isExperimentCohort {
+                    duckPlayer.settings.triggerNotification()
+                    experiment.duckPlayerMode = duckPlayer.settings.mode
+                }
             }
 
             experiment.fireYoutubePixel(videoID: videoID)