synapse workers default config: disable user_dir worker for now

(until https://github.com/matrix-org/synapse/issues/8787 is resolved)

roles/matrix-synapse/defaults/main.yml

@@ -291,7 +291,8 @@ matrix_synapse_workers_enabled_list:
   - { type: appservice, port: 00 }
   - { type: federation_sender, port: 0 }
   - { type: media_repository, port: 18221 }
-  - { type: user_dir, port: 18331 }
+# disable until https://github.com/matrix-org/synapse/issues/8787 resolved
+# - { type: user_dir, port: 18331 }
   - { type: frontend_proxy, port: 18441 }
 
 # Redis information