[DOCS] Document NOT as a simple_query_string flag

Fixes #7426
Test: Fixed pluggable transport module test to support transportclient

Also made sure, that only a change of requests is tested for and not
an initial value, which might not be set in case of a node client.
Tests: Improve test coverage.

Close #7428
Context suggester: infinite loop in GeolocationContextMapping

Close #7433
[TESTS] Temporarily disable FileBasedMappingsTests.