Currently ListEndpoint.take_action method unconditionally iterates
over all endpoints and issue GET /v3/services/<ep.service_id>
request for each endpoint. In case of HTTPS keystone endpoint this
can take significant amout of time, and it only getting worse in
case of multiple regions.
This commit change this logic to making just two GET requests: first
it gets endpoint list, then it gets service list, searching service
in the list instead of issuing GET /v3/services/<id> request.
Change-Id: I22b61c0b45b0205a2f5a4608c2473cb7814fe3cf
Closes-Bug: 1719413