ci: do not fail CI when Codecov test-results upload errors

The "Upload test results to Codecov" step in the unittest job is a
best-effort reporting side-channel, not a gate on code correctness. Set
fail_ci_if_error to false so a transient Codecov outage or upload error
no longer fails an otherwise passing build.

Co-Authored-By: Claude <svc-devxp-claude@slack-corp.com>

Author: WilliamBergamin

.github/workflows/ci-build.yml

@@ -129,7 +129,7 @@ jobs:
         uses: codecov/codecov-action@fb8b3582c8e4def4969c97caa2f19720cb33a72f # v7.0.0
         with:
           directory: ./reports/
-          fail_ci_if_error: true
+          fail_ci_if_error: false
           flags: ${{ matrix.python-version }}
           report_type: test_results
           token: ${{ secrets.CODECOV_TOKEN }}