enable shell-based rndc system tests

Enable existing rndc system tests (the python test function calling the
shell file was missing). Also update the extra artifacts list to remove
one generated file which was left behind.

(cherry picked from commit f84065a32c)

bin/tests/system/rndc/tests_sh_rndc.py

@@ -18,7 +18,7 @@ pytestmark = pytest.mark.extra_artifacts(
         "rndc.out.*",
         "ns2/*.jnl",
         "ns2/named.stats",
-        "ns2/named_dump.db.*",
+        "ns2/named_dump.db*",
         "ns2/nil.db",
         "ns2/other.db",
         "ns2/secondkey.conf",
@@ -37,3 +37,7 @@ pytestmark = pytest.mark.extra_artifacts(
         "ns7/test.db.jnl",
     ]
 )
+
+
+def test_rndc(run_tests_sh):
+    run_tests_sh()