Revert "feat(core): Update to Apollo Server v5"

This reverts commit b75e83b2
The @nestjs/apollo package v13.2.x still depends on the deprecated playground package,
which in turn depends on apollo server v4. This causes dependency conflicts that can
prevent installation of Vendure.

packages/core/package.json

@@ -40,14 +40,13 @@
         "cli/**/*"
     ],
     "dependencies": {
-        "@apollo/server": "^5.0.0",
-        "@as-integrations/express5": "^1.1.2",
-        "@graphql-tools/stitch": "^10.0.2",
-        "@nestjs/apollo": "^13.2.1",
-        "@nestjs/common": "^11.1.6",
-        "@nestjs/core": "^11.1.6",
-        "@nestjs/graphql": "^13.2.0",
-        "@nestjs/platform-express": "^11.1.6",
+        "@apollo/server": "^4.12.2",
+        "@graphql-tools/stitch": "^9.4.5",
+        "@nestjs/apollo": "~13.1.0",
+        "@nestjs/common": "^11.0.12",
+        "@nestjs/core": "^11.0.12",
+        "@nestjs/graphql": "~13.1.0",
+        "@nestjs/platform-express": "^11.0.12",
         "@nestjs/terminus": "^11.0.0",
         "@nestjs/typeorm": "^11.0.0",
         "@vendure/common": "3.4.3",