Revert "Load Xdebug, but do not enable it"

This reverts commit e011cbd.

Author: sebastianbergmann

.github/workflows/ci.yaml

@@ -55,8 +55,8 @@ jobs:
         uses: shivammathur/setup-php@v2
         with:
           php-version: 8.3
-          extensions: none, iconv, json, phar, tokenizer, xdebug
-          ini-values: xdebug.mode=off
+          extensions: none, iconv, json, phar, tokenizer
+          coverage: none
           tools: none
 
       - name: Run PHP-CS-Fixer