Implement MSC3890: Remotely silence local notifications (#14775)

docker/complement/conf/workers-shared-extra.yaml.j2

@@ -102,6 +102,8 @@ experimental_features:
   {% endif %}
   # Filtering /messages by relation type.
   msc3874_enabled: true
+  # Enable deleting device-specific notification settings stored in account data
+  msc3890_enabled: true
   # Enable removing account data support
   msc3391_enabled: true