[NEOS-1677] RemoveTeamAccountMember allows removing all users

[nickzelei]

I was the only user in an account and was able to remove myself from it, effectively orphaning my account.

We shouldn't allow people to do this. The proper way to do this here would be to have a delete account button.

This ticket should work the restriction in that prevents you from removing yourself if you are the last member of the account.

An integration test is also expected here to enforce this.

_{From SyncLinear.com | NEOS-1677}