Enhance ACL test on LT2 topology

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### Description of PR
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Summary:
This PR is to enhance ACL test on LT2 topology.
The change is done by updating port selection logic to include both upstream ports and downstream ports on LT2.
Depends on sonic-net/sonic-mgmt#19260

### Type of change

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- Fill x for your type of change.
- e.g.
- [x] Bug fix
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- [ ] Bug fix
- [ ] Testbed and Framework(new/improvement)
- [ ] New Test case
    - [ ] Skipped for non-supported platforms
- [x] Test case improvement

### Back port request
- [ ] 202205
- [ ] 202305
- [ ] 202311
- [ ] 202405
- [ ] 202411
- [ ] 202505

### Approach
#### What is the motivation for this PR?
This PR is to enhance ACL test on LT2 topology.

#### How did you do it?
The change is done by updating port selection logic to include both upstream ports and downstream ports on LT2.

#### How did you verify/test it?
The change is verified by running `test_acl` on a physical testbed.

#### Any platform specific information?
No.

#### Supported testbed topology if it's a new test case?
Not a new test.

### Documentation
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(If it's a new feature, new test case)
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Author: mssonicbld

tests/acl/test_acl.py

@@ -430,6 +430,13 @@ def setup(duthosts, ptfhost, rand_selected_dut, rand_unselected_dut, tbinfo,
                 acl_table_ports[''].append(k)
     elif topo == "t2":
         acl_table_ports = t2_info['acl_table_ports']
+    elif topo == "lt2":
+        # For LT2, add portchannels for downstream links
+        for k, v in list(port_channels.items()):
+            acl_table_ports[v['namespace']].append(k)
+        # Add RIF for upstream links
+        for namespace, port in list(upstream_ports.items()):
+            acl_table_ports[namespace] += port
     else:
         for namespace, port in list(upstream_ports.items()):
             acl_table_ports[namespace] += port