[action] [PR:16549] [dualtor] Fix testFdbMacLearning

[mssonicbld]

Description of PR

Summary:
Fixes # (issue)

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• New Test case
• Skipped for non-supported platforms
• Test case improvement

Back port request

• 202012
• 202205
• 202305
• 202311
• 202405
• 202411

Approach

What is the motivation for this PR?

testFdbMacLearning is flaky on dualtor.

Signed-off-by: Longxiang Lyu lolv@microsoft.com

How did you do it?

Let's toggle the mux ports to the random selected DUT, so all packets will be forwarded to it.

How did you verify/test it?

fdb/test_fdb_mac_learning.py::TestFdbMacLearning::testFdbMacLearning PASSED [100%]

================================================================================================================= 1 passed, 3 warnings in 1558.19s (0:25:58) =================================================================================================================

Any platform specific information?

Supported testbed topology if it's a new test case?

Documentation

[mssonicbld]

/azp run

[mssonicbld]

Original PR: #16549

[azure-pipelines]

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