Instances of nodetool generate random node name suffxes to facilitate running multiple simultaneous calls in parallel.  However, each time nodetool connects to the target node, a new atom is created on the latter.  If this happens frequently and/or long enough, it will eventually crash the node as it hits the atom table limit.  As a workaround, if the caller can guarantee calls are serialized and isolated in time, defining an env variable $NODETOOL_NODE_PREFIX will create identical atoms for node name prefix, thus avoiding generation of new atoms.

The proposed change is complimentary to erlware#868, aiming to address the issue, reported by one of our customers, in which a riak node hit the atom table limit (yes, all of 1M+ entries) and crashed. A postmortem showed the table filled with `[email protected]`, accumulated over a period of time resulting from calls to `riak admin status` every 5 min.

Note that I did not attempt to do any changes that may need to be done, to the same effect, in extended_bin_windows, as it's not straightforward for me which they would be (my knowledge of scripting in Windows is some 30 year old).