octavia-api's cli app doesn't behave well with haproxy so let's run
under apache and save ourselves some grief. Also adds cleanup for the
octavia-api tls proxy in update and upgrade tasks if it was previously
deployed.
Also updates zuul layout for multinode job to track changes to new
flattened octavia service files.
Closes-Bug: #1815811
Change-Id: Ied7cb31fbf1222694250e4769573bcbb82ba5bea
f4460a580d