refactor: 💡 change channel app state title & add alert msg (#2489)

* refactor: 💡 change channel app state title & add alert msg

✅ Closes: https://hashicorp.atlassian.net/browse/ICU-11148

addons/core/translations/resources/en-us.yaml

@@ -384,9 +384,9 @@ session-recording:
     messages:
       none:
         title: Channel Playback
-      missing:
-        title: We can't play back this channel because the file is missing
-        description: This likely means the connected storage bucket is misconfigured or the file was deleted.
+      error:
+        title: Playback error
+        description: This may mean the connected storage bucket is misconfigured, the file was deleted, or integrity validation failed.
         link: Retrieving lost session recordings
       not-supported:
         title: Playback is not supported for this channel