Support 2 vlan config in topology for test_acl (#16322)

What is the motivation for this PR?
If enable 2vlan config in topology file(such as ansible/vars/topo_t0-116.yml):
change from

    vlan_configs:
      default_vlan_config: one_vlan_a
to

    vlan_configs:
      default_vlan_config: two_vlan_a
Then vlan name is not Vlan1000 anymore, it could be Vlan100 or Vlan200.
So, in https://github.com/sonic-net/sonic-mgmt/pull/9334/files, it sets default vlan name to Vlan1000 in pytest_generate_tests for T0 is not very reasonable.

How did you do it?
So, in test_acl, for T0 topology, still get vlan name from config, not from vlan_name parameter, then test_acl can pass.

How did you verify/test it?
Run test_acl on testbed with 2vlan config.

tests/acl/test_acl.py

@@ -302,15 +302,22 @@ def setup(duthosts, ptfhost, rand_selected_dut, rand_unselected_dut, tbinfo, ptf
         DOWNSTREAM_DST_IP = DOWNSTREAM_DST_IP_M0_L3
         DOWNSTREAM_IP_TO_ALLOW = DOWNSTREAM_IP_TO_ALLOW_M0_L3
         DOWNSTREAM_IP_TO_BLOCK = DOWNSTREAM_IP_TO_BLOCK_M0_L3
-    if topo in ["t0", "mx", "m0_vlan"]:
+    if topo in ["mx", "m0_vlan"]:
         vlan_ports = [mg_facts["minigraph_ptf_indices"][ifname]
                       for ifname in mg_facts["minigraph_vlans"][vlan_name]["members"]]
 
         config_facts = rand_selected_dut.get_running_config_facts()
         vlan_table = config_facts["VLAN"]
         if "mac" in vlan_table[vlan_name]:
             vlan_mac = vlan_table[vlan_name]["mac"]
-
+    elif topo in ["t0"]:
+        vlan_ports = [mg_facts["minigraph_ptf_indices"][ifname]
+                      for ifname in list(mg_facts["minigraph_vlans"].values())[0]["members"]]
+        config_facts = rand_selected_dut.get_running_config_facts()
+        vlan_table = config_facts["VLAN"]
+        vlan_name = list(vlan_table.keys())[0]
+        if "mac" in vlan_table[vlan_name]:
+            vlan_mac = vlan_table[vlan_name]["mac"]
     # Get the list of upstream/downstream ports
     downstream_ports = defaultdict(list)
     upstream_ports = defaultdict(list)