Docs: Mention that that p/c queries and filters do not work in the delete-by-query api.
MLT Query: fix percent_terms_to_match

The parameter `percent_terms_to_match` (percentage of terms that must match in
the generated query) was wrongly set to the top level boolean query. This
would lead to zero or all results type of situations. This commit ensures that
the parameter is indeed applied to the query of generated terms.

Closes #7754
[CORE] Add ThreadPool.terminate to streamline shutdown

Shutting down threadpools and executor services is done in very similar
fashion across the codebase. This commit streamlines the process by
adding a terminate method to ThreadPool.
[TEST] Reenable threadleak filters with 5 sec. lingering
[TEST] add regular scroll REST test

Closes #7860
Add a listener thread pool
Today, when executing an action (mainly when using the Java API), a listener threaded flag can be set to true in order to execute the listener on a different thread pool. Today, this thread pool is the generic thread pool, which is cached. This can create problems for Java clients (mainly) around potential thread explosion.
Introduce a new thread pool called listener, that is fixed sized and defaults to the half the cores maxed at 10, and use it where listeners are executed.
relates to #5152
closes #7837
[TEST] improved regular scroll REST test

The intermediate document that gets indexed has now a non existing id, and we make sure it doesn't get returned.
[TRANSPORT] never send requests after transport service is stopped

With local transport or any transport that doesn't necessarily send
notification if connections are closed we might miss a node
disconnection and the request handler hangs forever / until the timeout
kicks in. This window only exists during shutdown and is likely
unproblematic in practice but tests might run into this problem when
local transport is used.
Aggs - support for arrays of numeric values in include/exclude clauses

Closes #7714
[TEST] improved regular scroll REST test

Added sort clause by field and checked docs returned each time