Cat Recovery API: Reverting changes introduced with commit e1c75bae87300f5fd59c9a455f9a89298688df49

Adding these 2 headers to the CAT Recovery made the CI tests hanging for a loooong time.

Related to #8041
Updated paths to be inline with #8240
Docs: Update multi-get.asciidoc

Duplicate word

Closes #8228
Test: Change missing/null alias test to catch a request error, not a param error

Relates: #7863
Make indexQueryParserService available. Closes #8248
Tests: Refixed the put_alias tests

The missing/null index parameter is in the URL, not the body.
So it should be required, and throw a param error if not provided.

Relates #7863
Introduce elasticsearch.in.bat (i.e. es.in for Windows)

Break-out common functionality between elasticsearch.bat and service.bat
Relates #8237

(cherry picked from commit 87095e79534bcef97b2b275322c924bd96b34e3b)
Improve handling of multicast binding exceptions

In case the multicast binding fails (due to socket errors), abort zen
pinging code and throw a better error message
Relates #8225

(cherry picked from commit f819cff77a0ef95b340afc2f22e3464283803960)
Enabled overriding the request headers in the clients

One can set the headers sent with request by the clients by setting the `request.headers` setting. This commit enables overriding any such set headers directly on the requests.
Use the simpler command line syntax in the Debian init script

It's definitely not a blocker, but it would be nice to be consistent.

Closes #5033
Added missing percolate API parameters (percolate_routing, percolate_preference) to the REST API Spec

Closes #7173
[ENGINE] Add current translog ID to commit meta before closing

Today we simply close the IW when we have to open a new one if ie.
we change merge settings. Yet, the API is deprecated and under the hood
it commits the IW. For safety we should add the current translog ID and
use rollback instead to not wait for merges.
s/MapBuilder/singletonMap in InternalEngine
Tests: stop printing all thread stacks on failure: it's too noisy
Test: fix test to optimize and flush in the end to try to prevent 'Delete Index failed - not acked'
Completion Suggester: Fix CompletionFieldMapper to correctly parse weight
 - Allows weight to be defined as a string representation of a positive integer

closes #8090
[TEST] initialize SUITE | GLOBAL scope cluster in a private random context

Today any call to the current randomized context modifies the random
sequence such that cluster initialization is context dependent. If due
to an error for instance a static util method is used like `randomLong`
inside the TestCluster instead of the provided Random instance all
reproducibility guarantees are gone. This commit adds a safe mechanism
to initialize these clusters even if a static helper is used. All none
test scope clusters are now initialized in a private randomized context.
[TEST] Move rebalance setting to the index level / pass it on index creation
[SCRIPTS] GetIndexedScript call can deadlock

GetIndexedScript can deadlock since they perform blocking operation
on the network thread. This commit moves the blocking to an async operation
MLT Field Query: remove it from master

The MLT field query is simply replaced by a MLT query set to specififc field.
To simplify code maintenance we should deprecate it in 1.4 and remove it in
2.0.

Closes #8238