tc-testing: flush gact actions on test teardown

Test 6fb4 creates one mirred and one pipe action, but only flushes mirred
on teardown. Leaking pipe action causes failures in other tests.

Add additional teardown command to also flush gact actions.
Signed-off-by: NVlad Buslov <vladbu@mellanox.com>
Acked-by: NJamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tools/testing/selftests/tc-testing/tc-tests/actions/mirred.json

@@ -44,7 +44,8 @@
         "matchPattern": "action order [0-9]*: mirred \\(Egress Redirect to device lo\\).*index 2 ref",
         "matchCount": "1",
         "teardown": [
-            "$TC actions flush action mirred"
+            "$TC actions flush action mirred",
+            "$TC actions flush action gact"
         ]
     },
     {