Fix test cases in integrated.test_multiprocess_api

Fixes bug #1098043

Be patient in test_multiprocess_api while waiting service to be spawned or
killed, because:
    * Service spawning has a limit of one process a second.
    * A test server in the cloud might have limited resources,
      the time there might be several times slower.

Change-Id: If75e6dfa5d769985a6c1b46461f25485e2a996ad
Merge "Fix test cases in integrated.test_multiprocess_api"