Clear login token once apppassword is generated

Fixes #7697

When using the new login flow a token will be generated since we login.
However after that we generate yet another token to return (as we
should).

However we should kill the current session token as we are done with it.
And will never use it again.

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>