[QA] no logout from identity provider possible

See with android App version ownCloud release Version 3.0.1 (5e553f078)

Actual behaviour

• I have an owncloud server that requires login via keycloak idp (using the server openidconnect app version 2.2.0-rc.1)
• Connect android app with the server, the IDP broweser window opens, I can choose a user and log in. OK
  
• Use the trashcan icon to delete the account again.
• Connect again (without waiting more than 10 minutes)
  • The IDP immediately authorizes the app, without showing a user password dialog. BAD
  • There is no way to choose a differnet user for this server. BAD.
• Wait 10 Minutes. Connect to the same server again.
  • A message appears saying my token is expired, I need to log in.
    

• Click "Einloggen" (log in). The app refreshes, again without asking for username or password and files are now accessible for the original user.
  

• Note, that the expired message remains at the bottom of the screen, and upload does not work. BAD.
• have to click "Einloggen" again. After that, the message is gone and upload works. Okayish

Tell us what should happen.

• when the account is removed, it should also be logged out from the IDP, so that any remainng session tokens are invalidated.
• it should always be possible to choose the username, after entering a server URL.

Start by reproducing the Android app flow with a server using Keycloak and the server OpenID Connect app: add an account, remove it, reconnect within 10 minutes, and retry after token expiry. Check the account-removal and login flows for IDP session handling and expired-token state. Done means removing an account invalidates the remaining IDP session, users can choose a username on reconnect, and the expired message does not block uploads after login.