Fix(ci): Upload xcodebuild logs on failure for better debugging

  The xcbeautify tool, while useful for cleaning up xcodebuild output, can truncate long or multi-line error messages. This is particularly problematic
  for configuration errors that occur early in the build process, making it difficult to diagnose the root cause from the GitHub Actions logs alone.

  This change adds a step to the xcodebuild job in the Firestore workflow to upload the raw xcodebuild-*.log file as a build artifact whenever a failure
  occurs. This ensures that the full, untruncated log is always available for download and inspection, facilitating more effective debugging.

Author: ncooke3

.github/workflows/firestore.yml

@@ -386,6 +386,13 @@ jobs:
         export EXPERIMENTAL_MODE=true
         scripts/third_party/travis/retry.sh scripts/build.sh Firestore ${{ matrix.target }} xcodebuild
 
+    - name: Upload xcodebuild logs
+      if: failure()
+      uses: actions/upload-artifact@v4
+      with:
+        name: xcodebuild-logs-${{ matrix.target }}
+        path: xcodebuild-*.log
+
   pod_lib_lint:
     needs: check
     strategy: