Add comment and set context key if not in exp

Author: joyceerhl

src/client/datascience/data-viewing/dataViewerExperimentEnabler.ts

@@ -11,12 +11,16 @@ export class DebuggerDataViewerExperimentEnabler implements IExtensionSingleActi
         @inject(IExperimentService) private readonly experimentService: IExperimentService
     ) {}
     public async activate() {
+        // This context key controls the visibility of the 'View Variable in Data Viewer'
+        // context menu item from the variable window context menu during a debugging session
         const isDataViewerExperimentEnabled = new ContextKey(
             'python.isDebuggerDataViewerExperimentEnabled',
             this.commandManager
         );
         if (await this.experimentService.inExperiment('debuggerDataViewer')) {
             await isDataViewerExperimentEnabled.set(true);
+        } else {
+            await isDataViewerExperimentEnabled.set(false);
         }
     }
 }