use fqcns for some task

Signed-off-by: Sebastian Gumprich <github@gumpri.ch>

roles/matrix-synapse/tasks/import_media_store.yml

@@ -51,7 +51,7 @@
 # This can only work with local files, not if the media store is on Amazon S3,
 # as it won't be accessible in such a case.
 - name: Ensure provided media store directory is synchronized
-  synchronize:
+  ansible.builtin.synchronize:
     src: "{{ server_path_media_store }}/"
     dest: "{{ matrix_synapse_media_store_path }}"
     delete: true