Rename `geohashgrid` to `geohash_grid` in documentation.

It was renamed in fc6bc4c4776a2f710f57616e3495aaf6a230c4d3.

Close #4997
Does not support "script" in value_clunt aggregation.
[DOC] Tidied up geohashgrid aggregations
[TEST] thrown error when there are no REST tests to run
Fix hashCode values of aggregations' BytesValues.

This commit removes FilterBytesValues which is very trappy as the default
implementation forwards all method calls to the delegate. So if you do any
non-trivial modification to the terms or to the order of the terms, you need
to remember to override currentValueHash, copyShared, and this is very
error-prone.

FieldDataSource.WithScript.BytesValues and ScriptBytesValues now return correct
hash codes, future bugs here would be catched by the new assertion in
SortedUniqueBytesValues.

This bug was causing performance issues with scripts as all terms were assumed
to have the same hash code.

Close #5004
[DOCS] Deprecated the path setting in favour of copy_to

Relates to #4729
Add S3 and HDFS repositories
[DOCS] add azure and gce discovery plugins

Clean EC2 disco doc
Add Azure disco doc
Add Google Compute Engine doc
Fix Zen doc (add `enabled` in `multicast` parameters list) - Fix #5032.
Ignore case when parsing `script_values_sorted|unique` in aggregations.

Close #5009
[DOCS] Removed the experimental label from Tribe, Hot Threads
and Completion Suggester
[DOCS] Updated migration docs for multi_field to point to copy_to
[DOCS] Fix terms agg value script example
[DOCS] Make apt/yum repos more visible
Updated nodes info endpoint in elasticsearch.yml

Relates to #4055
Fixed the string() code literal in the java client index api doc.
[DOCS] organize a bit the repository plugins
Add Marvel and Paramedic to config file
add redis transport plugin
[DOCS] delete by query requires a top-level query parameter

Closes #5044
Fix BytesRef owning issue in string terms aggregations.

The byte[] array that was used to store the term was owned by the BytesRefHash
which is used to compute counts. However, the BytesRefHash is released at some
point and its content may be recycled.

MockPageCacheRecycler has been improved to expose this issue (putting random
content into the arrays upon release).

Number of documents/terms have been increased in RandomTests to make sure page
recycling occurs.

Close #5021