For each of the 34 roles (3 clients, 9 bots, 22 bridges), this commit:
- Adds `_restart_necessary: false` default variable
- Adds `register:` directives to config/image/systemd tasks
- Computes `_restart_necessary` via set_fact (OR of all .changed results)
- Wires `(_restart_necessary | bool)` in group_vars/matrix_servers
This allows the systemd service manager to skip unnecessary restarts
when running install-* tags and nothing actually changed.
Service roles and complex multi-service roles will follow separately.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This was useful when the order of these roles in relation to Synapse
mattered (when we were injecting stuff into Synapse variables during
runtime). This is no longer the case since 0ea7cb5d18, so all of
this can be removed.