Reduce min-ready

The round-robin-under-contention allocator in nodepool gives
min-ready values too much importance.  Reduce them so that we
are not wasting nodes.

Note, this should be considered a temporary measure until the
allocator is improved.

Change-Id: I0a3921036ee2f6842d11a09f9ee1506e465c6d52
Merge "Reduce min-ready"