Ensure /etc/mysql/my.cnf removal

Additional fix to conflicting mysql config files
in order to fix mysql syslog logging in Ubuntu.
For simple deployment (custom_setup_class undef):
* /etc/mysql/my.conf should be used in Ubuntu
For HA case for Centos/Ubuntu:
* /etc/mysql/my.conf should be absent
* /etc/my.cnf should be used
(Note that changes are Fuel OSCI packaging specific)

Closes-bug: #1349601

Change-Id: I56c1b5ebca2553d341fe0498451075294f3e651f
Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
Merge "Ensure /etc/mysql/my.cnf removal"