Use LDAP filters defined in config.yaml for team syncing

When LDAP is enabled, users have the ability to use team syncing. Unfortunately, the method for syncing uses a memberOf filter exclusively and ignores filters defined via config.yaml file:

https://github.com/quay/quay/blob/d14da17a401caed79e87a3685b554a0007e5de51/data/users/externalldap.py#L415

This is problematic for some users who have specific LDAP setups. The suggestion would be to use filters defined in Quay's config.yaml file or, if they aren't defined, default back to memberOf.