perf test: Replace grep perl regexp with awk

perf test: Replace grep perl regexp with awk

perl is not universal on all machines and should be replaced with awk,
which is much more common.

Before:
  $ perf test "probe libc's inet_pton & backtrace it with ping" -v
  --- start ---
  test child forked, pid 145431
  grep: Perl matching not supported in a --disable-perl-regexp build

  FAIL: could not add event
  ---- end(-1) ----
  121: probe libc's inet_pton & backtrace it with ping                 : FAILED!
After:
  $ perf test "probe libc's inet_pton & backtrace it with ping" -v
  121: probe libc's inet_pton & backtrace it with ping                 : Ok

Suggested-by: Ian Rogers <irogers@google.com>
Signed-off-by: Chun-Tse Shao <ctshao@google.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Link: https://lore.kernel.org/r/20250620174034.819894-1-ctshao@google.com
[ fold James' suggestion not to escape _ in the event pattern. ]
Signed-off-by: Namhyung Kim <namhyung@kernel.org>