Roles affected: appservice-discord, appservice-irc, beeper-linkedin,
heisenbridge, hookshot, mautrix-bluesky, mautrix-discord,
mautrix-gmessages, mautrix-googlechat, mautrix-signal, mautrix-slack,
mautrix-twitter, mautrix-whatsapp, mautrix-wsproxy, mx-puppet-groupme,
mx-puppet-steam, postmoogle, sms, steam, cactus-comments, element,
fluffychat, schildichat, conduit, corporal, dendrite,
ldap-registration-proxy, media-repo, pantalaimon,
prometheus-nginxlog-exporter, registration, sygnal, synapse-admin,
user-verification-service.

For each role: renamed _docker_image* variables to _container_image*
(and _docker_src_files_path to _container_src_files_path where
applicable), added deprecation entries in validate_config.yml, and
updated group_vars/docs references.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/4445

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

`-t` works on both old and new Docker versions, so it's best to use that.

This is an attempt at optimizing service startup.

The effect is most pronounced when many services are restarted one by one.
The systemd service manager role sometimes does this - for example when `just install-service synapse` runs.
In such cases, a 5-second delay for each Synapse worker service
(or other bridge/bot service that waits on the homeserver) quickly adds up to a lot.

When services are all stopped fully and then started, the effect is not so pronounced, because
`matrix-synapse.service` starts first and pulls all worker services (defined as `Wants=` for it).
Later on, when the systemd service manager role "starts" these worker services, they're started already.
Even if they had a 5-second wait each, it would have happened in parallel.