Fix generic qf not showing qs from user context on load

[jacbn]

Also adds a few tests to check this in future.

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In as brief as I can, the user object is sometimes available on load (if you came via soft redirect), and sometimes not (if not). This means our original populateFiltersFromAccountSettings function was not running on soft reload, because the user object had not changed (thus not triggering the useEffect).

I have fixed this by pulling the logic from populateFiltersFromAccountSettings into external functions, which are also used in the initial values for searchStages and searchExamBoards provided the user is available then. This means that no matter when the user is available, we always run the same logic.

[jacbn]

This isn't strictly part of the fix for this PR, but this kills off stale requests before they update state later which fixes a lot of random inconsistency with tests! :)

[codecov]

Codecov Report

❌ Patch coverage is 94.28571% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 42.60%. Comparing base (640fa15) to head (6ef0186).

Files with missing lines	Patch %	Lines
src/app/components/pages/QuestionFinder.tsx	94.28%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1936      +/-   ##
==========================================
+ Coverage   42.35%   42.60%   +0.25%     
==========================================
  Files         575      575              
  Lines       24390    24411      +21     
  Branches     8085     8056      -29     
==========================================
+ Hits        10330    10401      +71     
+ Misses      13396    13346      -50     
  Partials      664      664              

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