wait for green in tests for now
Fixes related to accepted docs not taken into account:
* Removed the applyAcceptedDocs in ChildrenConstantScoreQuery, they need to be applied at all times. (because of short circuit mechanism)
* Moved ParentDocSet to FilteredDocIdSetIterator, because it fits better than MatchDocIdSet.
* Made similar changes to ParentConstantScoreQuery for consistency between the two queries. The bug accepted docs bug didn't occur in the ParentConstantScoreQuery.
* Updated random p/c tests to randomly update parent or child docs during the test run.

Closes #4306
Also short circuit within segment when score mode is avg
Make the ChildrenQuery and ParentQuery not rely on the fact that score of 0 means that there isn't a match.
add more ensureGreen to aggs tests
Log intermediate pending searchers as trace instead of debug
The short circuit mechanism always needs to be wrapped with the live docs. In certain scenarios the live docs isn't passed down with acceptedDocs.
For example when a has_child is wrapped in a filtered query as query and the wrapped filter is cached.
The short circuit mechanism in that case counts down based on deleted docs, which then yields lower results than is expected.

Relates to #4306
Added random filtered query logic the to random parent query tests.
Fixed bug in ParentQuery.ChildScorer#advance(), the parent value was checked for the _uid field while the _parent should have been checked.
Changed the "script_lang" parameter to "lang" in all value source based aggs - to be consistent with all other script based APIs.
[DOCS] Fixed typos and corrected grammar
only wrap the parentFilter in ApplyAcceptedDocsFilter, not the other short circuit filters.
fix mapping error in p/c benchmarks
added more wait for green status on aggs tests
Use EA#assertMatchCount() over just checking the match count.
User minimum_master_nodes in tests that shutdown nodes some of those time out on Windows
Use EA#assertMatchCount() over just checking the match count.
[DOCS] Typos in aggregations
[DOCS] Changed the _cat docs to use ?v instead of ?v=true
[DOCS] Linked cat-pending to cluster-pending
[DOCS] Another cat?v change