fix(TopBar): do not fetch events if actor is a guest or it is not ini…

[DorraJaouad]

…tialized yet

☑️ Resolves

• Upcoming events fetch API is only accessible to users.
• Ref: https://github.com/nextcloud/server/blob/6d6baec54f3ebaf3d3917a58aa5281a7a21e738b/apps/dav/lib/Controller/UpcomingEventsController.php#L50-L52

🖌️ UI Checklist

🖼️ Screenshots / Screencasts

Before

After
nothing

🏁 Checklist

• 🌏 Tested with different browsers / clients:
  • Chromium (Chrome / Edge / Opera / Brave)
  • Firefox
  • Safari
  • Talk Desktop
  • Not risky to browser differences / client
• 🖌️ Design was reviewed, approved or inspired by the design team
• ⛑️ Tests are included or not possible
• 📗 User documentation in https://github.com/nextcloud/documentation/tree/master/user_manual/talk has been updated or is not required

[Antreesy]

/backport to stable30

[Antreesy]

/backport to stable30.0