Merge branch 'convert-tests-to-libbpf'

Andrii Nakryiko says:

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There were few more tests and samples that were using custom perf buffer setup
code from trace_helpers.h. This patch set gets rid of all the usages of those
and removes helpers themselves. Libbpf provides nicer, but equally powerful
set of APIs to work with perf ring buffers, so let's have all the samples use

v1->v2:
- make logging message one long line instead of two (Song).
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>