Cancel delay connection timers in lcb_wait()

Also use lcb_wait in MockUnitTest.testBufferRelocationOnNodeFailover
At this moment we don't have enough public API to implement lcb_wait()
on the user's side completely. So it is better not to use raw
IO-objects in the timeout-sensitive tests

Change-Id: I77544f55215101770e1dd59bc2bdd0d9cda8d4de