Clean up token on deauthorize

[AlexTugarev]

Bug description

When disconnecting a provider, tokens should be deleted as well.

Steps to reproduce

Go to /integrations page and disconnect a previously connected provider.

Expected behavior

No response

Example repository

No response

Related to #3754

Additional information

• on account deletion / reconnecting with the same account the tokens will be cleaned up ✅
• on connecting with another account (after previously disconnecting from first account) the old token remains ❌
  • in such cases, no tokens are returned (the DB interface and the getToken operation will throw an error,) thus unauthorized access is prevented ✅
  • further there is an re-authorization request in place when trying to open a workspace for the affected git provider, which will clean up the situation on success ✅

TL;DR the UX is impacted as it looks like the authorization is missing ❌