Blacklist 096-array-copy-concurrent-gc on debuggable & gcstress & debug & host.

It has been consitently timing out lately.

Bug: 149708943
Test: 096-array-copy-concurrent-gc
Change-Id: I1659d6a0a2b822088a2e01a87b37ff8af033a838
diff --git a/test/knownfailures.json b/test/knownfailures.json
index afddc81..1dd4fe3 100644
--- a/test/knownfailures.json
+++ b/test/knownfailures.json
@@ -1343,5 +1343,11 @@
         "tests": ["2029-contended-monitors"],
         "variant": "interpreter | interp-ac | gcstress | trace",
         "description": ["Slow test. Prone to timeouts."]
+    },
+    {
+        "tests": ["096-array-copy-concurrent-gc"],
+        "variant": "gcstress & debuggable & debug & host",
+        "bug": "b/149708943",
+        "description": ["Timeouts."]
     }
 ]