SNOW-1065172-gh-workflow-optimization: allow codecov upload to fail

Sometimes on GCP this test stalls. Until we figure out what is the real
prblem we will retry and add timeout.

.github/workflows/build_test.yml

@@ -223,9 +223,9 @@ jobs:
       - name: Uplaod to codecov
         uses: codecov/codecov-action@v4
         with:
-          directory: artifacts/coverage.xml_*/coverage.xml
+          file: combined_coverage.xml
           env_vars: OS,PYTHON
-          fail_ci_if_error: true
+          fail_ci_if_error: false
           flags: unittests
           token: ${{ secrets.CODECOV_TOKEN }}
           verbose: true