Disable 2246-trace-stream on debug-gc config

2246-trace-stream is timing out on debug-gc configuration. Temporary
disable while we investigate the issue

Bug: 264844668
Test: art/test.py -t 2246-trace-stream
Change-Id: I2ed60d21671279a1c5694326c2b5a1cef9cf42df
diff --git a/test/knownfailures.json b/test/knownfailures.json
index 1855429..5f79b21 100644
--- a/test/knownfailures.json
+++ b/test/knownfailures.json
@@ -1549,5 +1549,11 @@
         "description": ["Change of behavior when used with JDK 17."],
         "bug": "b/242985234",
         "variant": "jvm"
+    },
+    {
+        "tests": ["2246-trace-stream"],
+        "env_vars": {"ART_TEST_DEBUG_GC": "true"},
+        "bug": "b/264844668",
+        "description": ["Test timing out on debug gc."]
     }
 ]