Prevent caption from swallowing taps if no overlay needed.

app/src/main/java/org/thoughtcrime/securesms/stories/viewer/page/StoryViewerPageFragment.kt

@@ -581,6 +581,7 @@ class StoryViewerPageFragment :
         }
       } else {
         caption.setOnClickListener(null)
+        caption.isClickable = false
       }
     }
   }