When we don't use localhost as deploy host, we need to use
octavia_service_setup_host_python_interpreter variable.
This variable give the correct python path (in a venv for example when
we use a utility container as a setup host)
Depends-On: I270c0b623aef55bd6bf80b9bf5fdd618e4ced517
Change-Id: I65c023db3cb8080e57442f35e599a372519d97d7
Closes-Bug: 1835744