[HttpClient] Minor refactor

[vishweshbankwar]

Fixes #
Design discussion issue #

Changes

Please provide a brief description of the changes here.

Merge requirement checklist

• CONTRIBUTING guidelines followed (nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

Merging #5164 (4df24d4) into main (a736574) will decrease coverage by 0.02%.
Report is 1 commits behind head on main.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5164      +/-   ##
==========================================
- Coverage   83.46%   83.45%   -0.02%     
==========================================
  Files         297      297              
  Lines       12368    12366       -2     
==========================================
- Hits        10323    10320       -3     
- Misses       2045     2046       +1     

Flag	Coverage Δ
unittests	83.45% <100.00%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...ementation/HttpHandlerMetricsDiagnosticListener.cs	88.23% <100.00%> (-0.23%)	⬇️
...plementation/HttpWebRequestActivitySource.netfx.cs	80.77% <100.00%> (-0.04%)	⬇️

... and 7 files with indirect coverage changes