Remove unused code
Wire utf-8 encoding, so unicode filenames work

Sets -Dfile.encoding=UTF-8 by default.

Closes #8847
[TEST] Make parent breaker check less strict

In cases of heavy contention, it's possible for more than 2 threads
to race to a circuit breaking exception.

Essentially this means that if we have 3 threads all trying to add 3 and
simultaneously cause a circuit breaking exception (due to retry), when
adjusting after circuit breaking we can "rewind" past what this test
expects the child breaker to be at.

This adds leeway into the check, where it's okay to be within
NUM_THREADS from the parentLimit, because each thread should only add 1
to the breaker at a time.
Update repositories.asciidoc

Update formatting of PGP key
Docs: typo on "frequent"

I replaced "high frequent terms" with "high frequency terms" and "low frequent terms" with "low frequency terms".

Alternatively, we could write, "highly frequent terms" and "minimally frequent terms" (or just "rare terms").

Closes #8962
Settings: Remove `mapping.date.round_ceil` setting for date math parsing

The setting `mapping.date.round_ceil` (and the undocumented setting
`index.mapping.date.parse_upper_inclusive`) affect how date ranges using
`lte` are parsed.  In #8556 the semantics of date rounding were
solidified, eliminating the need to have different parsing functions
whether the date is inclusive or exclusive.

This change removes these legacy settings and improves the tests
for the date math parser (now at 100% coverage!). It also removes the
unnecessary function `DateMathParser.parseTimeZone` for which
the existing `DateTimeZone.forID` handles all use cases.

Any user previously using these settings can refer to the changed
semantics and change their query accordingly. This is a breaking change
because even dates without datemath previously used the different
parsing functions depending on context.

closes #8598
closes #8889
Shutdown indices service last

We do wait for shards to be closed in IndicesService for 30 second.
Yet, if somebody holds on to a store reference ie. an open scroll request
the 30 seconds time-out and node shutdown takes very long. We should
release all other resources first before we shutdown IndicesService.

Closes #8940
Add toString() to IndexShardGateway
Refactor InternalLock and SearchFactory out of InternalEngine
Pass in warmer and similarity service, instead of retrieving them from engine
WIP add of ShadowEngine