FilterDirectory.getPendingDeletions does not delegate, fixed
temporarily by overriding in StoreDirectory.
This in turn caused duplicate file name use after a trimUnsafeCommits
had been done, since a new IndexWriter would not consider the pending
deletes in IndexFileDeleter. This should only happen on windows (AFAIK).
Reenabled doing index updates for all tests using
IndexShardTests.indexOnReplicaWithGaps (which could fail due to above
when using mocked WindowsFS).
Added getPendingDeletions delegation to all elasticsearch
FilterDirectory subclasses that were not trivial test-only overrides to
minimize the risk of hitting this issue in another case.
bf444b9f02