Move any external replication settings to the new master in case of a failover with galeramon

Set up:

• a galera cluster with a maxscale in front using galeramon
• the "master" is configured to replicate from an external server
  Action:
• shut down the local master

Desired result:

• the external replication settings should get transferred to the new local master and the replication should continue (same as when using a primary/replica cluster with mariadbmon)
  Actual result:
• the external replication settings are not transferred and are lost; external replication stops

It would be useful to have the desired result as then external replication could be much more robust