CI: tracking: publish tests results to Kernel CI

[matttbe]

KCIDB is collecting results from different CIs. It would be nice to publish our tests results there to have all tests in a central point, but also to benefit from their infrastructure: tracking regressions and flaky tests.

Note that KCIDB dashboard is currently down for different reasons. At the same time, a new API is coming. It should allow us to publish tests and get the tracking part.

Or use another way to track regressions and flaky tests

[matttbe]

It might be enough to use this for the moment: https://ci-results.mptcp.dev/flakes.html