Rename _requires_restart to _migration_requires_restart across all custom roles

These variables track whether a database migration necessitates a service
restart. The new name avoids confusion with the conditional restart
feature introduced in af193043/9accc848/4a8df138, where
devture_systemd_service_manager handles restarting services whose
configuration or image changed. The old _requires_restart name was
ambiguous — it could be mistaken for the systemd_service_manager
mechanism — so _migration_requires_restart makes the purpose explicit.

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

roles/custom/matrix-bridge-mautrix-whatsapp/tasks/setup_install.yml

@@ -18,7 +18,7 @@
 ---
 
 - ansible.builtin.set_fact:
-    matrix_mautrix_whatsapp_requires_restart: false
+    matrix_mautrix_whatsapp_migration_requires_restart: false
 
 - when: "matrix_mautrix_whatsapp_database_engine == 'postgres'"
   block:
@@ -43,7 +43,7 @@
               pgloader_options: ['--with "quote identifiers"']
 
         - ansible.builtin.set_fact:
-            matrix_mautrix_whatsapp_requires_restart: true
+            matrix_mautrix_whatsapp_migration_requires_restart: true
 
 - name: Ensure Mautrix Whatsapp paths exists
   ansible.builtin.file:
@@ -171,4 +171,4 @@
     name: "matrix-mautrix-whatsapp.service"
     state: restarted
     daemon_reload: true
-  when: "matrix_mautrix_whatsapp_requires_restart | bool"
+  when: "matrix_mautrix_whatsapp_migration_requires_restart | bool"