BPF CI update: traffic monitor logs

["Ihor Solodrai" <ihor.solodrai@linux.dev>]

Hi everyone.

Traffic monitor logs for selftests/bpf are now collected and uploaded
as artifacts on BPF CI. Currently only on x86_64.

You can download them from github job artifacts for a run that you're
interested in.

For example: https://github.com/kernel-patches/bpf/actions/runs/14115935817
Scroll down to the artifacts and there you can find archives with a
name pattern like this:

    tmon-logs-${ARCH}-${TOOLCHAIN}-${TEST_RUNNER}

For example:

    tmon-logs-x86_64-gcc-test_progs_no_alu32

These logs are also available if the test run fails.

Happy debugging!