Fix GitHub Actions workflow failures

- Add WP_PHPUNIT__DIR and WP_TESTS_DIR environment variables to PHPUnit workflow to fix 'WP_UnitTestCase not found' error
- Increase WordPress Playground server timeout from 60s to 180s with better progress logging to fix timeout failures
- Add conditional checks for SONAR_TOKEN and CODACY_PROJECT_TOKEN to gracefully skip analysis when tokens are not set
- Properly handle server process lifecycle in Playground tests (capture PID, kill on completion)

.github/workflows/sonarcloud.yml

@@ -27,7 +27,18 @@ jobs:
         with:
           fetch-depth: 0  # Shallow clones should be disabled for a better relevancy of analysis
 
+      - name: Check if SonarCloud token is set
+        id: check_token
+        run: |
+          if [ -z "${{ secrets.SONAR_TOKEN }}" ]; then
+            echo "SONAR_TOKEN is not set, skipping SonarCloud analysis"
+            echo "skip=true" >> $GITHUB_OUTPUT
+          else
+            echo "skip=false" >> $GITHUB_OUTPUT
+          fi
+
       - name: SonarCloud Scan
+        if: steps.check_token.outputs.skip != 'true'
         uses: SonarSource/sonarqube-scan-action@master
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}  # Needed to get PR information, if any