Keep Centos 7 based CI/promo jobs passing when configuring Apache MPM

[Bogdan Dobrelya]

Use MPM prefork for Centos 7/Fedora CI Train jobs

For Centos 7, apache RPM hardcodes prefork MPM in
/etc/httpd/conf.modules.d/00-mpm.conf. That cannot be properly
configured with container puppet tasks in t-h-t because as of RHEL 8 OS
family, apache module configs reside in /etc/httpd/conf.d and there is
no more /etc/httpd/conf.modules.d.

To w/a that for Centos 7 CI in Train, always use MPM prefork, so there
is no more multiple MPM modules configuration conflicts.

There is no other/clean way for Kolla startup scripts to pick those OS
version dependent paths for kolla configs in t-h-t.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/674588

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/674604

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/675653

[OpenStack Infra (hudson-openstack)]

Change abandoned by Bogdan Dobrelya (bogdando) (<email address hidden>) on branch: master
Review: https://review.opendev.org/674604

[OpenStack Infra (hudson-openstack)]

Change abandoned by Bogdan Dobrelya (bogdando) (<email address hidden>) on branch: master
Review: https://review.opendev.org/675653

[wes hayutin (weshayutin)]

Bogdan, is this still an issue?

[Bogdan Dobrelya (bogdando)]

@Wes, not an alert, just a requirement to allow https://review.opendev.org/#/c/674588/10 passing CI. I think it will be postponed until U, there we would need no to keep this w/a and will have Centos 8 images in CI.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Bogdan Dobrelya (bogdando) (<email address hidden>) on branch: master
Review: https://review.opendev.org/674604