ep_test_apis: Make wait_for_flusher_to_settle() a no-op when Ephemeral
ep_test_apis: Make wait_for_flusher_to_settle() a no-op when Ephemeral

Ephemeral has no flusher, and hence there's nothing to wait for.

Change-Id: Ie25ff6be253cdb347db459737bef5b0cc699a914

daverigby/ep-engine,daverigby/ep-engine,daverigby/ep-engine,daverigby/ep-engine