guestagent/mysql: Remove unused function
guestagent/mysql: Remove unused function

This commit remove the dead function
`replace_mycnf_with_template`.

Closes-bug: 1351361
Change-Id: Ie9a17a972e069b27740c96188f176271599142f4

zhujzhuo/openstack-trove,openstack/trove,hplustree/trove,fabian4/trove,mmasaki/trove,hplustree/trove,zhangg/trove,mmasaki/trove,redhat-openstack/trove,zhangg/trove,cp16net/trove,redhat-openstack/trove,fabian4/trove,zhujzhuo/openstack-trove,cp16net/trove,zhujzhuo/openstack-trove,mmasaki/trove,changsimon/trove,changsimon/trove,openstack/trove,cp16net/trove,fabian4/trove,redhat-openstack/trove,changsimon/trove