Add MySQL service restart to activate my.cnf change

Closes-Bug: #1242949

backport: havana

Change-Id: Ie6270c13f2fbd2578ac68b89edfbce2e415ba5e3
(cherry picked from commit 24e4aaf8bdc23a15f1bb2d0c527194fd7abfbb11)
Merge "Add MySQL service restart to activate my.cnf change" into stable/havana