Unset the matrix gerritbot uid:gid settings

We thought the latest image would be happy based on updates that
tristanC made. Unfortunately ssh complains with:

  2021-12-06 18:33:14.616 [ThreadId 19]: [ERROR] ssh process exited: 255
  2021-12-06 18:33:15.618 [ThreadId 19]: Connecting to review.opendev.org:29418
  No user exists for uid 11000

Undo only the uid:gid settings as the new image seems to work otherwise.

Change-Id: I9c0963ea5c78cecb99e0070b06f9ebd8876a3157

playbooks/roles/matrix-gerritbot/templates/docker-compose.yaml.j2

@@ -6,7 +6,9 @@ services:
   gerritbot-matrix:
     image: {{ gerritbot_matrix_image }}
     network_mode: host
-    user: "{{ gerritbot_uid }}:{{ gerritbot_gid }}"
+    # TODO: Continue sorting out how to make this work with the
+    # image published by SF.io
+    #user: "{{ gerritbot_uid }}:{{ gerritbot_gid }}"
     restart: always
     logging:
       driver: syslog