[HEALTH] Don't mark health as timed out if desired state is reached

Today we mark cluster health requests as timed out if the request has already
timed out. Yet, and implementation detail of the health request is that we are
waiting for events which can take quite some time if the machine is busy. If
we have already reached a valid state while waiting for events to be processed
we shouldn't mark the clusterstate as timed-out. This will help tests that
wait for green state with lots of nodes and shards to not fail the cluster health
calls.