Fix failing tests after react_server_client_manifest_file changes

- Add react_server_client_manifest_file parameter to mock_bundle_configs helper
- Update react_server_client_manifest_file_path tests to mock bundle_js_file_path instead of public_bundles_full_path
- Ensure trailing newline in spec file

These changes fix the CI failures introduced by using bundle_js_file_path for manifest resolution.

Co-authored-by: Abanoub Ghadban <AbanoubGhadban@users.noreply.github.com>

Author: github-actions[bot]