CORE-1652 Changes to address potential MySQL startup race

Core-1652 identifies that due to MySQL being started at boot, a
number of expected steps can fail unexpectedly.

This change delineates the controller and controllerMgmt node
init sequences, and explicitly stops MySQL prior to the steps
where it would normally be started on a controller, which will
will allow os-collect-config to run, and ultimately RabbitMQ to
start as expected.

Change-Id: Id783ee08a175a3d17ce38046de290dc214bac274