fix(settings): verify hello-v1 response (shared secret)

[Antreesy]

☑️ Resolves

• Follow-up to fix(AdminSettings): test Websocket connection #13973

🖌️ UI Checklist

🖼️ Screenshots / Screencasts

🏚️ Before	🏡 After
Screenshot before	Screenshot after

🚧 Tasks

Although I'm unable to catch failed secret:

Maybe, there is no actual request made (as in Listener.php; BackendNotifier.php)

🏁 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

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🛠️ API Checklist

🚧 Tasks

• ...

🏁 Checklist

• ⛑️ Tests (unit and/or integration) are included or not possible
• 📘 API documentation in docs/ has been updated or is not required
• 🔖 Capability is added or not needed