Add debugging and error handling to PHPUnit workflow

- Add verbose logging to install-wp-tests.sh step
- Make mysqladmin create non-fatal (database may already exist)
- Add echo statements to track installation progress

This helps diagnose the "Install WordPress test suite" failure
and prevents failures when database already exists.

🤖 Generated with [Qoder][https://qoder.com]

.github/workflows/phpunit.yml

@@ -51,7 +51,10 @@ jobs:
 
       - name: Install WordPress test suite
         run: |
+          set -e
+          echo "Installing WordPress test suite with multisite=${{ matrix.multisite }}"
           bash bin/install-wp-tests.sh wordpress_test root root 127.0.0.1 ${{ matrix.wp }} false ${{ matrix.multisite && 'true' || 'false' }}
+          echo "WordPress test suite installed successfully"
 
       - name: Run PHPUnit tests
         run: |