[TEST] Make sure that there are no relocating shards before taking snapshot

Temporary workaround for #5531
[TEST] Added extra test for multi fields with default `include_in_all` settings, in which only the main field should end up in the `_all` field.
add uppercase token filter

closes #5539
Fix for zero-sized content throwing off toChannelBuffer(). Also
short-circuit writeTo(..) accordingly to avoid unnecessary work.

Fixes #5543
Capture and set start time in Delete By Query operations

This is important for queries/filters that use `now` in date based queries/filters

Closes #5540
Assorted fixes for bugs in the PagedBytesReference tests, plus a typo
where the wrong variable was used for a calculation.

Closes #5549
[DOCS] fixed typo

Closes #5272
[TEST] Increase logging on MinDocCountTests.
Convert TermQuery to PrefixQuery if PHRASE_PREFIX is set

We miss to add a single term to a prefix query if the query in only a
single term.

Closes #5551
[DOCS] Clarify nested type documentation
[TEST] Moved wipe* methods, randomIndexTemplate & ensureEstimatedStats from ElasticsearchIntegrationTest to TestCluster

This is the first to make it possible to have a different impl of TestCluster (e.g. based on an external cluster) that has the same methods but a different impl for them (e.g. it might use the REST API to do the same instead of the Java API)

Closes #5542
[TEST] removed leftover ElasticsearchIntegrationTest#randomIndexTemplate

used cluster().randomIndexTemplate instead
Remove deprecated gateways

Closes #5422
Fixes a bug when the field has been configured with eager fielddata loading, the fielddata is not being loaded.

Closes #5557
Fixed space in licence header.
Now really fix eager fielddata loading.

Relates to #5557
Initial layout / design for global ordinals
Initial cut at adding global ordinal based terms aggregator.
Also implemented copyShared() properly for global ordinal based field data impl.
Removed unnecessary layer of abstraction in fetching the global ords and the the actual terms from global ords.
Moved the data structures the GlobalIndexFieldData (before BaseGlobalIndexFieldData) instead of keep them around in FixedGlobalOrdinals.
Introduced a hash and direct based terms global ordinals implementations
Slightly adjusted the benchmark