Adding flaky attribute for tests.
diff --git a/build.json b/build.json
index 96437d0..2079b2c 100644
--- a/build.json
+++ b/build.json
@@ -866,7 +866,8 @@
         "grpc",
         "gpr_test_util",
         "gpr"
-      ]
+      ],
+      "flaky": true
     },
     {
       "name": "fling_test",
@@ -880,7 +881,8 @@
         "grpc",
         "gpr_test_util",
         "gpr"
-      ]
+      ],
+      "flaky": true
     },
     {
       "name": "gen_hpack_tables",