Fix conflicting my.cnf for Ubuntu

In order to enable mysql syslog logging for Ubuntu,
ensure mysql conf file path is /etc/my.cnf instead
of /etc/mysql/my.cnf default.

Closes-bug: #1349601

Change-Id: I31757e622a412623e5e4624008aaaf9be4280636
Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
Merge "Fix conflicting my.cnf for Ubuntu"