unexpected behavior when logging out

[tomholub]

reproduce:

1. install app
2. Continue with Gmail, and authenticate with account A
3. while it's loading backups on setup screen, kill the app (maybe the same could be achieved by waiting until it's done loading, then choosing "use another account". The point is that the app will receive and save access tokens for account A, but setup won't be finished)
4. re-open the app to again see "Continue with Gmail". Now continue with account B
5. actually finish setup of account B
6. menu -> log out

expected behavior: I should see splash screen with "Continue with Gmail"

actual behavior: takes me to "Set up FlowCrypt" where it loads backups for account A (I'm not expecting this after I just logged out of account B)

[tomholub]

tested on #323