[CORE] Free pending search contexts if index is closed

Today we hold on to search context reference if they are not cleaned
up for a while until a reaper thread trashes them if they timed out.
This commit removes all pending contexts once the index is closed to release
resources and filehandles immediatly once the index is closed.
[BLOOM] Fix Bloom filter ram usage calculation

BloomFilter actually returned the size of the bitset as the
size in bytes so off by factor 8 plus a constant :)

Closes #8564
Disable bloom filters.

make the "es090" postings format read-only, just to support old segments. There is a test version that subclasses it with write-capability for testing.

Closes #8571
Update DiskThresholdDecider javadoc

Since v1.3.0, and issue #6201, the default values in code and documentation have been updated to 85% and 90% for low and high watermarks. However, the related javadoc still contains the initial values : this commit fix this.
Aggregations: Fix geohash grid doc counts computation on multi-valued fields.

Close #8512
[CORE] Ensure shards are deleted under lock on close

Today there is a race condition between the actual deletion of
the shard and the release of the lock in the store. This race can cause
rare imports of dangeling indices if the cluster state update loop
tires to import the dangeling index in that particular windonw. This commit
adds more safety to the import of dangeling indices and removes the race
condition by holding on to the lock on store closing while the listener
is notified.