perf test: Move PERF_SAMPLE_WEIGHT_STRUCT parsing to common test

test__x86_sample_parsing is identical to test__sample_parsing except
it explicitly tested PERF_SAMPLE_WEIGHT_STRUCT. Now the parsing code
is common move the PERF_SAMPLE_WEIGHT_STRUCT to the common sample
parsing test and remove the x86 version.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250724163302.596743-22-irogers@google.com


Signed-off-by: Namhyung Kim <namhyung@kernel.org>