selftests/tc-testing: Add a test case for DRR class with TC_H_ROOT

Integrate the reproduer from Mingi to TDC.

All test results:

1..4
ok 1 0385 - Create DRR with default setting
ok 2 2375 - Delete DRR with handle
ok 3 3092 - Show DRR class
ok 4 4009 - Reject creation of DRR class with classid TC_H_ROOT

Cc: Mingi Cho <mincho@theori.io>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250306232355.93864-3-xiyou.wangcong@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/tc-testing/tc-tests/qdiscs/drr.json

@@ -61,5 +61,30 @@
         "teardown": [
             "$TC qdisc del dev $DUMMY handle 1: root"
         ]
+    },
+    {
+        "id": "4009",
+        "name": "Reject creation of DRR class with classid TC_H_ROOT",
+        "category": [
+            "qdisc",
+            "drr"
+        ],
+        "plugins": {
+            "requires": "nsPlugin"
+        },
+        "setup": [
+            "$TC qdisc add dev $DUMMY root handle ffff: drr",
+            "$TC filter add dev $DUMMY parent ffff: basic classid ffff:1",
+            "$TC class add dev $DUMMY parent ffff: classid ffff:1 drr",
+            "$TC filter add dev $DUMMY parent ffff: prio 1 u32 match u16 0x0000 0xfe00 at 2 flowid ffff:ffff"
+        ],
+        "cmdUnderTest": "$TC class add dev $DUMMY parent ffff: classid ffff:ffff drr",
+        "expExitCode": "2",
+        "verifyCmd": "$TC class show dev $DUMMY",
+        "matchPattern": "class drr ffff:ffff",
+        "matchCount": "0",
+        "teardown": [
+            "$TC qdisc del dev $DUMMY root"
+        ]
     }
 ]