Examine the tx counters in WRRtest instead of counting what arrives

[byu343]

Description of PR

Summary: test/test_qos_sai.py testQosSaiDwrr causes a burst of traffic to be transmitted by the DUT, but the intervening network between the DUT and PTF may not be capable of handling the entire burst of packets at full linerate. Instead inspect the packet transmit counters on the appropriate interface to ensure that at least the correct number of packets were transmitted, and ensure that at least 1 of the packets are observed at PTF. Fixes # (issue)

Type of change

• [x] Bug fix
• [ ] Testbed and Framework(new/improvement)
• [ ] Test case(new/improvement)

Back port request

• [ ] 202012
• [ ] 202205
• [ ] 202305
• [ ] 202311
• [x] 202405

Approach

What is the motivation for this PR?

test/test_qos_sai.py testQosSaiDwrr causes a burst of traffic to be transmitted by the DUT, but the intervening network between the DUT and PTF may not be capable of handling the entire burst of packets at full linerate.

How did you do it?

Instead inspect the packet transmit counters on the appropriate interface to ensure that at least the correct number of packets were transmitted, and ensure that at least 1 of the packets are observed at PTF.

How did you verify/test it?

The test can pass after the change.

Any platform specific information?

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

Documentation