TC-DGETH-2.2: Automate

[cecille]

There's no reason this can't be automated. The real problem is that the example app doesn't report the packet counts correctly. An assert should be added that the packet count is > 0

The one caveat is that I'm not sure the example apps DO this correctly, so if that's the case, this might be an extensive fix to populate these fields in the linux apps.

test plan: https://github.com/CHIP-Specifications/chip-test-plans/blob/master/src/cluster/ethernet_diagnostics.adoc
current script: https://github.com/project-chip/connectedhomeip/blob/master/src/app/tests/suites/certification/Test_TC_DGETH_2_2.yaml