Remove Unnecessary mysql::server Dependency

Previously, the db::mysql class required mysql::server.  This is
unnecessary since the mysql::db define requires the mysql::config
class for db creattion.  Additionally, this prevents users from
using a different class such as galera::server to manage
the database.

Change-Id: I9216891e6ec29a8429aad1bb73b7f4fe7f22b2c1
Merge "Remove Unnecessary mysql::server Dependency"