apache: switch to use the apache worker mpm

Fixes: #9169

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>
apache: change template to load mpm worker module

in apache 2.4

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>
Merge pull request #211 from ceph/wip-apache-worker

apache: switch to use the apache worker mpm

Reviewed-by: Sage Weil <sage@redhat.com>