[StyleCleanUp] Use literals where appropriate (CA1802)

[h3xds1nz]

I've prepared this PR but then just realized that #10382 needs to be done first to prevent havoc, so gonna draft this.

Fixes #10724

Description

Swaps use of static readonly fields for const where appropriate. This in some cases saves allocations.

Note that naming issues will be taken care of in a separate issue to reduce diffs.

Customer Impact

Decreased allocations, a bit of perf.

Regression

No.

Testing

Local build.

Risk

Low, just an analyzer fix. The only issue would be reflection-based changes that will no longer be possible but there's no point of supporting these anyways, we'd never move anywhere.

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 11.20563%. Comparing base (72af9a5) to head (4dab672).
Report is 1 commits behind head on main.

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main      #10725         +/-   ##
===================================================
- Coverage   11.25778%   11.20563%   -0.05216%     
===================================================
  Files           3315        3313          -2     
  Lines         665229      665139         -90     
  Branches       74668       74668                 
===================================================
- Hits           74890       74533        -357     
- Misses        589035      589307        +272     
+ Partials        1304        1299          -5     

Flag	Coverage Δ
Debug	11.20563% <100.00000%> (-0.05216%)	⬇️

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