DuckPlayer: Temporary Fix for Watch In Youtube (#3437)

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

**Description**:
There is an issue in the Frontend that causes `allowFirstVideo` to
remain 'true' even if it shouldn't. This issue is triggered by sending
more than one User-Settings Message per webpage view.

Moving this into the enrollment conditional, will buy us time to fix the
issue in the FE and C.S.S and release as part of the regular release
train.

DuckDuckGo/DuckPlayer/DuckPlayerNavigationHandler.swift

@@ -229,15 +229,15 @@ 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)