The prometheus-proxy service is called octavia-prometheus-proxy in RDO's
RPMs [0].
Add a svc-map for the service name to fix the amphora-agent element for
these distros.
[0] https://review.rdoproject.org/r/c/openstack/octavia-distgit/+/44152
Partial-Bug: 1992668
Change-Id: Ie739cd582103d1aab3021c56654e395b5919358f
(cherry picked from commit 344d6d76ce)