octavia: add amphora-interface binary

This binary was added with [1].

[1] - https://review.opendev.org/c/openstack/octavia/+/761195/

Change-Id: I1c80b786450b4829eebbbd0b92493eaa7ceb944d

openstack/octavia/octavia.spec.j2

@@ -326,6 +326,7 @@ exit 0
 %license LICENSE
 %{_bindir}/amphora-agent
 %{_bindir}/amphora-health-checker
+%{_bindir}/amphora-interface
 %{_unitdir}/openstack-octavia-amphora-agent.service
 %if 0%{?suse_version}
 %{_sbindir}/rc%{name}-amphora-agent