auth_info_ttl makes server to hang

[bugy]

When auth_info_ttl option is enabled, time to time server hangs on user credentials refresh

Reported by @miksir:

it happens when state expire triggered and server going to update info to gitlab. When server hung there is no message "AbstractOauthAuthenticator.INFO] Loaded groups for" in logs
as I can see you saving state to gitlab_auth.json by timer now? may be there is some deadlock happens

[bugy]

Fixed, I was using a wrong lock (a normal one) in coroutines. Apparently, that was a bad idea
I didn't manage to reproduce the problem with proper coroutine locks