ctdb-scripts: Only consider statistics on timeout

ctdb-scripts: Only consider statistics on timeout

Checking statistics is only really relevant to timeouts.  That is, if
an rpcinfo times out it is worth checking if the service making
progress.  If the RPC service is not registered then the statistics
don't need to be checked because they shouldn't be changing.

The 2 previously added tests added to check statistics progress now
behave identically and fail on all iterations.  To support testing
with "timeouts", an optional TIMEOUT flag can now be added to the RPC
service passed to nfs_iterate_test().  2 new tests are added to
exercise the new behaviour.

The 2 new "if" statements in nfs_iterate_test() could be combined.
However, a subsequent commit would split them and would be more
difficult to read.

Signed-off-by: Martin Schwenke <mschwenke@ddn.com>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>