Tidy up after I4aa104920, dropping declaration of absented resources

* Drop declarations of mpm_worker.conf.
* Uncomment apache2 service restarts.
* Recurse into conf-enabled/*.conf.
* Drop unused template mpm_worker.conf.erb.

Change-Id: Ib4b3ad27152c0d574db2b5d00babdc600ab66c53
Merge "Tidy up after I4aa104920, dropping declaration of absented resources" into production