Fix acl/test_stress_acl.py invalid interface name (#15796)

Description of PR
Fix acl/test_stress_acl.py using bad interface name for ACL table creation

Summary:
Fixes # (issue)
In acl/test_stress_acl.py, it attempts to retrieve an interface that can be used to create a ACL table. DUTs with and without PortChannels require different methods respectively.

Currently, it checks by filtering with topo. However, some topology flags can have configurations that have or not have PortChannels, making topos no longer a sufficient check - in some topos the test will fail with:

Error: Failed to parse ACL table config: exception=Cannot bind ACL to specified port Ethernet136
Reproducible by manually running the following on the DUT:

config acl add table DATAACL L3 -s ingress -p Ethernet0
^FAILS
config acl add table DATAACL L3 -s ingress -p PortChannel101
^WORKS

Author: justin-wong-ce

tests/acl/test_stress_acl.py

@@ -91,12 +91,15 @@ def prepare_test_file(rand_selected_dut):
 @pytest.fixture(scope='module')
 def prepare_test_port(rand_selected_dut, tbinfo):
     mg_facts = rand_selected_dut.get_extended_minigraph_facts(tbinfo)
-    if tbinfo["topo"]["type"] == "mx":
-        dut_port = mg_facts["minigraph_acls"]["DataAcl"][0]
-    else:
-        dut_port = list(mg_facts['minigraph_portchannels'].keys())[0]
+
+    ports = list(mg_facts['minigraph_portchannels'])
+    if not ports:
+        ports = mg_facts["minigraph_acls"]["DataAcl"]
+
+    dut_port = ports[0] if ports else None
+
     if not dut_port:
-        pytest.skip('No portchannels found')
+        pytest.skip('No portchannels nor dataacl ports found')
     if "Ethernet" in dut_port:
         dut_eth_port = dut_port
     elif "PortChannel" in dut_port: