Fix mysql client config generation with containerized environment

Fix mysql client config generation with containerized environment

When the tripleo::profile::base::database::mysql::client profile is
included by other openstack services, the file /etc/my.cnf.d/tripleo.cnf
is not generated because docker-puppet is configured to disregard the
exec tags.

Make the profile use either File or Exec resource based on how it's
being called, to make it work for both containerized and non-containerized
use cases.

Change-Id: I103baa02373f6713cc300ac039a6f173ff0bbf1c