[acl] Add regression test for config acl CLI command (sonic-net#1694)

Add a new test case to catch the bug where calling "config acl add table" multiple
times causes the "ports" field to be deleted from config DB.

Signed-off-by: Danny Allen <daall@microsoft.com>

tests/test_acl_cli.py

@@ -0,0 +1,33 @@
+class TestAclCli:
+    def test_AddTableMultipleTimes(self, dvs, dvs_acl):
+        dvs.runcmd("config acl add table TEST L3 -p Ethernet0")
+
+        cdb = dvs.get_config_db()
+        cdb.wait_for_field_match(
+            "ACL_TABLE",
+            "TEST",
+            {"ports": "Ethernet0"}
+        )
+
+        # Verify that subsequent updates don't delete "ports" from config DB
+        dvs.runcmd("config acl add table TEST L3 -p Ethernet4")
+        cdb.wait_for_field_match(
+            "ACL_TABLE",
+            "TEST",
+            {"ports": "Ethernet4"}
+        )
+
+        # Verify that subsequent updates propagate to ASIC DB
+        L3_BIND_PORTS = ["Ethernet0", "Ethernet4", "Ethernet8", "Ethernet12"]
+        dvs.runcmd(f"config acl add table TEST L3 -p {','.join(L3_BIND_PORTS)}")
+        acl_table_id = dvs_acl.get_acl_table_ids(1)[0]
+        acl_table_group_ids = dvs_acl.get_acl_table_group_ids(len(L3_BIND_PORTS))
+
+        dvs_acl.verify_acl_table_group_members(acl_table_id, acl_table_group_ids, 1)
+        dvs_acl.verify_acl_table_port_binding(acl_table_id, L3_BIND_PORTS, 1)
+
+
+# Add Dummy always-pass test at end as workaroud
+# for issue when Flaky fail on final test it invokes module tear-down before retrying
+def test_nonflaky_dummy():
+    pass