fix(codecov): update codecov-upload.yml action to upload report with correct path (#34814)

### Reason for this change
Fixing the upload path for codecov-upload.ymp based workflow


### Description of changes
Last successful run of CodeCov report was https://github.com/aws/aws-cdk/actions/runs/15032809949/job/42248762782
which uploaded to certain path configured in codecov

Uploads after that have been failing silently due to path match failures in codecov

Creating the path `./coverage/packages/aws-cdk-lib/core/coverage` and uploading to it should allow code coverage to be populated again

### Checklist
- [ ] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: kumvprat

.github/workflows/codecov-upload.yml

@@ -24,15 +24,15 @@ jobs:
         uses: actions/download-artifact@v4
         with:
           name: coverage-artifacts
-          path: ./coverage
+          path: ./coverage/packages/aws-cdk-lib/core/coverage
           github-token: ${{ secrets.GITHUB_TOKEN }}
           repository: ${{ github.repository }}
           run-id: ${{ github.event.workflow_run.id }}
 
       - name: Upload to Codecov
         uses: codecov/codecov-action@v5
         with:
-          files: ./coverage/packages/aws-cdk-lib/coverage/cobertura-coverage.xml
+          files: ./coverage/packages/aws-cdk-lib/core/coverage/cobertura-coverage.xml
           fail_ci_if_error: true
           flags: suite.unit
           use_oidc: true