Related to:
- https://github.com/mautrix/meta/releases/tag/v0.4.0
- https://mau.fi/blog/2024-09-mautrix-release/

It seems like the new version does not support a `/metrics` endpoint.
We skip keep the Ansible variables, but they're not doing anything.

* mautrix-meta: enable spaces; add a hint into the display name

* use the meta mode to determine displayname suffix

* Allow for people to easily unset the mautrix-meta displayname suffix

Previously, unsetting `matrix_mautrix_meta_messenger_bridge_displayname_suffix`
or (`matrix_mautrix_meta_instagram_bridge_displayname_suffix`) variable would
make you end up witha trailing space in `displayname`.

It's possible that mautrix-meta trims this, but I haven't checked. It's
better not to risk it anyway.

---------

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

Related to: https://github.com/mautrix/facebook/issues/332

Fixes: https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3138