Add okhttp-4 integration to supported-configurations.json

The split okhttp-4.0 module registers a new "okhttp-4" integration name,
so DD_TRACE_OKHTTP_4_ENABLED must be declared in the supported
configurations metadata.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: dougqh

metadata/supported-configurations.json

@@ -8361,6 +8361,14 @@
         "aliases": ["DD_TRACE_INTEGRATION_OKHTTP_3_ENABLED", "DD_INTEGRATION_OKHTTP_3_ENABLED"]
       }
     ],
+    "DD_TRACE_OKHTTP_4_ENABLED": [
+      {
+        "version": "A",
+        "type": "boolean",
+        "default": "true",
+        "aliases": ["DD_TRACE_INTEGRATION_OKHTTP_4_ENABLED", "DD_INTEGRATION_OKHTTP_4_ENABLED"]
+      }
+    ],
     "DD_TRACE_OKHTTP_ANALYTICS_ENABLED": [
       {
         "version": "A",