Use mariadb-galera-server for server package

For Icehouse, mariadb-galera-server will be the default database
server. This patch sets the server package name in the template, which
overrides the default value in the puppet module.

Change-Id: Icdb00dba5d75878cdd8d7a16c0b71ae9182d64ba
Merge "Use mariadb-galera-server for server package"