Removed Legacy AtB Guaranteed SPAs

[IllianiCBT]

Removed hard-coded logic for SPA gain when improving personnel from Regular -> Veteran and Veteran -> Elite.

Legacy AtB has personnel automatically gain SPA when reaching Veteran and Elite ratings. Personnel acquired off the market have a random chance of 0-2 SPAs, plus those guaranteed SPAs.

SPAs cost around 50 xp each. Hitting Elite will cost 170-340 xp (depending on whether it's a one or two skill profession). That means buying an Elite character from the personnel market is the equivalent of getting 320-540+ xp for effectively free.

Furthermore, these hardcoded SPA improvements cause problems for anyone wanting to play using CamOps, as they need to manually remove the hardcoded SPAs prior to adding their own picks.

While the second issue could be resolved by adding a campaign option to disable fixed SPAs, I would prefer that we remove hardcoded SPA gains entirely. The benefit of being able to grab an Elite character from the market with 2-4 SPAs already acquired is simply too powerful. Being able to hire Elites is already a no-brainer, they don't need to also arrive with a few hundred xp of SPAs too.

Note: characters can still spawn with 0-2 random SPAs, with higher rated characters more likely to appear with a random SPA. This PR only removes the guaranteed SPAs gained from hitting Veteran and Elite (or spawning at Veteran or Elite).

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 10.51%. Comparing base (bce5f63) to head (7c69d3c).
Report is 42 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5225      +/-   ##
============================================
- Coverage     10.52%   10.51%   -0.01%     
+ Complexity     6047     6040       -7     
============================================
  Files           957      957              
  Lines        134523   134482      -41     
  Branches      19545    19527      -18     
============================================
- Hits          14154    14147       -7     
+ Misses       119018   118985      -33     
+ Partials       1351     1350       -1     

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