master_host has 60 character limit, increase to 255 bytes

Customer needs to have master_host parameter longer than 60 characters. When they tried using longer than 60 characters, its report errors as follow.
ERROR 1470 (HY000): String 'cmdb7102-mariadb-1.mymaxhostname-for-mariadb-test.svc.cluster.local' is too long for MASTER_HOST (should be no longer than 60)

System is installed with master-slave with maxscale configuration. When change master command is executed on slave with master_host with more than 60 characters then it fail.

Customer would ideally want to be able to put in the maximum fully qualified domain name size of 255
Customer is on 10.3.23 (CS)