Fixed Contract Multiplier Again

[IllianiCBT]

• Reorganized the employer multiplier logic to match CamOps.
• Fixed a bug where we were using the full Reputation Rating and not Reputation Modifier.
• Refactored difficulty modifier by ensuring calculations only occur for positive difficulty values. This likely wouldn't have changed anything, but it's cleaner so better.

Fix #5934

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 10.28%. Comparing base (3cd1c2e) to head (4a75538).
Report is 23 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5937      +/-   ##
============================================
- Coverage     10.29%   10.28%   -0.01%     
+ Complexity     6127     6123       -4     
============================================
  Files          1038     1039       +1     
  Lines        139206   139326     +120     
  Branches      20620    20633      +13     
============================================
- Hits          14336    14335       -1     
- Misses       123462   123587     +125     
+ Partials       1408     1404       -4     

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