Reenable HA (#20226)

* Reenable HA

* Changelog

* Remove unncessary changelog

Author: sethsamuel

mysql/datadog_checks/mysql/mysql.py

@@ -104,6 +104,7 @@ class MySql(AgentCheck):
     REPLICA_SERVICE_CHECK_NAME = 'mysql.replication.replica_running'
     GROUP_REPLICATION_SERVICE_CHECK_NAME = 'mysql.replication.group.status'
     DEFAULT_MAX_CUSTOM_QUERIES = 20
+    HA_SUPPORTED = True
 
     def __init__(self, name, init_config, instances):
         super(MySql, self).__init__(name, init_config, instances)