chore: Move 'main' benchmark to shared workers temporarily

[scottgerring]

While we're blocked getting the dedicated workers pool going, let's move main's benchmark back to shared so that it stops failing in the meantime.

Changes

Please provide a brief description of the changes here.

Merge requirement checklist

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.1%. Comparing base (867e2a1) to head (1aed675).
Report is 2 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #2889   +/-   ##
=====================================
  Coverage   81.1%   81.1%           
=====================================
  Files        124     124           
  Lines      23927   23927           
=====================================
  Hits       19410   19410           
  Misses      4517    4517           

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