Install test_server.bin in well known location

This patch installs and uses test_server.bin from
/opt/octavia-tempest-plugin as a well known location on the
filesystem. This way tests, like grenade, that run the devstack
plugins once in /old paths, can find the binary when running from
/new paths.

Change-Id: Ia78f16fde026269dec01f4dceb202842ad12a557
3 files changed