feat: refactor, invert ifs, use optimal methods

[TimothyMakkison]

• Remove unused using statements
• Invert ifs
• Use TryGetValue
• Remove unneeded ToArray
• Make local function static
  Reverts changes made in feat: custom query key formatters #1570

I can't guarantee that I've caught everything. Future PR needs to rerun csharpier

[codecov]

Codecov Report

Attention: Patch coverage is 83.63636% with 9 lines in your changes missing coverage. Please review.

Project coverage is 86.50%. Comparing base (6ebeda5) to head (8365e59).
Report is 34 commits behind head on main.

Files	Patch %	Lines
Refit/RequestBuilderImplementation.cs	83.63%	5 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1713      +/-   ##
==========================================
- Coverage   87.73%   86.50%   -1.23%     
==========================================
  Files          33       34       +1     
  Lines        2348     2068     -280     
  Branches      294      295       +1     
==========================================
- Hits         2060     1789     -271     
+ Misses        208      201       -7     
+ Partials       80       78       -2     

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[ChrisPulman]

Thank you @TimothyMakkison