template metric toggle for mautrix bridges supporting it

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

@@ -78,6 +78,9 @@ matrix_mautrix_twitter_appservice_bot_username: twitterbot
 # Specifies the default log level for all bridge loggers.
 matrix_mautrix_twitter_logging_level: WARNING
 
+# Whether or not metrics endpoint should be enabled.
+matrix_mautrix_twitter_metrics_enabled: false
+
 # Default configuration template which covers the generic use case.
 # You can customize it by controlling the various variables inside it.
 #