Jason Tedor c70c440050 Adjust status on bad allocation explain requests
When a user requests a cluster allocation explain in a situation where
it does not make sense (for example, there are no unassigned shards), we
should consider this a bad request instead of a server error. Yet, today
by throwing an illegal state exception, these are treated as server
errors. This commit adjusts these so that they throw illegal argument
exceptions and are treated as bad requests.

Relates #25503
2017-06-30 17:50:20 -04:00
..
2017-06-30 14:22:20 -04:00