Remove release mode test steps from CI

[Kyle-Ye]

Summary

• Remove "Build and run tests in release mode" step from macOS workflow
• Remove "Building and running tests in release mode" step from Ubuntu workflow
• Debug test + coverage steps remain unchanged

Test plan

• Verify macOS CI workflow runs successfully without release test step
• Verify Ubuntu CI workflow runs successfully without release test step

[augmentcode]

🤖 Augment PR Summary

Summary: Simplifies CI by removing the extra SwiftPM swift test -c release runs from the macOS and Ubuntu GitHub Actions workflows.

Changes: Keeps the existing debug-mode test, coverage generation, and Codecov upload steps unchanged.

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[augmentcode]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 27.49%. Comparing base (6c991c1) to head (2139e1d).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #818   +/-   ##
=======================================
  Coverage   27.48%   27.49%           
=======================================
  Files         661      661           
  Lines       42429    42425    -4     
=======================================
+ Hits        11661    11663    +2     
+ Misses      30768    30762    -6     

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