[skip ci] Disable Xdebug for now

It currently fails already during configure for PHP >= 8.5.0.

Author: cmb69

.github/workflows/nightly.yml

@@ -876,6 +876,7 @@ jobs:
           repository: phpredis/phpredis
           path: redis
       - name: git checkout xdebug
+        if: false
         uses: actions/checkout@v4
         with:
           repository: xdebug/xdebug
@@ -937,6 +938,7 @@ jobs:
           ./configure --prefix=/opt/php --with-php-config=/opt/php/bin/php-config
           make -j$(/usr/bin/nproc)
       - name: build xdebug
+        if: false
         run: |
           cd xdebug
           /opt/php/bin/phpize