Randomize numeric types in MLT test and apply mapping ahead of time.
Add ESAbortPolicy to cached pools

All ES ThreadPools / Executors should use the ESAbortPolicy or at least
one that throws the ESRejectedExecutionException.
Introduce base test classes to share thread scope annotations

Currently we run unittests with clusters running in the background
that can potentiallly spawn threads causeing the thread leak control
to fire off in tests that don't use the test cluster. This commit
introduces some base classes for that purpose shadowning lucene test
framework classes adding the approriate ThreadScope.
Wait for consistent view on both clients in ClusterServiceTests
Improve assertion and busy waiting for RecoveryWhileUnterLoadTests
Use awaiBusy rather than a tight loop in IndicesStoreTests