perf test: Add skip to --per-thread test

As reported in:
https://lore.kernel.org/linux-perf-users/20220428122821.3652015-1-tmricht@linux.ibm.com/
the 'instructions:u' event may not be supported. Add a skip using 'perf
record'.

Switch some code away from pipe to make the failures clearer.

Reported-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Thomas Richter <tmricht@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: https://lore.kernel.org/r/20220505182505.3313191-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>