Use wait_until in create_test_server to wait for server ACTIVE

In some testcases, waiters.wait_for_server_status(..., 'ACTIVE') after
self.create_test_server() can be replaced by self.create_test_server(
wait_until='ACTIVE').

Change-Id: Idb9dbfee830344e4087972c59b444b477d3a0c05
2 files changed