Rework and expand QueryPhaseTests (#96889)

There are a number of issues with the current tests included in
QueryPhaseTests that this commit addresses:
- many scenarios tested in the same single test method that can be split
  up into multiple test methods
- the search context is shared across subsequent test sections, and
  modified for each scenarios, which makes it hard to follow exactly
what scenario each section tests
- some scenarios are tested multiple times
- code duplication around indexing docs, create and close dir and reader

The added code coverage revolves around support for terminate_after,
which was only tested in combination with the scenario where total hit
count can be shortcut. Added scenario where it cannot be shortcut.

Author: javanna