[ticket/11386] Send list of migrations instead of using load_migrations

Remove dependency of extension manager for migrator.

Keeping load_migrations function for others to use if they desire
but requiring the finder be sent to it in order to use it.

PHPBB3-11386

phpBB/config/migrator.yml

@@ -10,8 +10,6 @@ services:
             - %core.php_ext%
             - %core.table_prefix%
             - @migrator.tool_collection
-        calls:
-            - [set_extension_manager, [@ext.manager]]
 
     migrator.tool_collection:
         class: phpbb_di_service_collection

phpBB/config/services.yml

@@ -116,12 +116,11 @@ services:
             - @service_container
             - @dbal.conn
             - @config
+            - @migrator
             - %tables.ext%
             - %core.root_path%
             - .%core.php_ext%
             - @cache.driver
-        calls:
-            - [set_migrator, [@migrator]]
 
     ext.finder:
         class: phpbb_extension_finder