Ketesa needs the MAS admin API exposed to perform MAS-specific
operations (registration tokens, sessions, emails, etc.) when MAS
is in use.
The admin still needs to provision an admin token for Ketesa
manually, but at least the listener resource is now ready by default.
Mirrors the existing Synapse admin API auto-enable pattern.
Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/5164