template metric toggle for mautrix bridges supporting it

roles/custom/matrix-bridge-mautrix-whatsapp/defaults/main.yml

@@ -47,6 +47,10 @@ matrix_mautrix_whatsapp_logging_level: 'warn'
 # If false, created portal rooms will never be federated.
 matrix_mautrix_whatsapp_federate_rooms: true
 
+# Whether or not metrics endpoint should be enabled.
+matrix_mautrix_whatsapp_metrics_enabled: false
+
+
 # Database-related configuration fields.
 #
 # To use SQLite, stick to these defaults.