perf test: Add stat uniquifying test

perf test: Add stat uniquifying test

The `stat+uniquify.sh` test retrieves all uniquified `clockticks` events
from `perf list -v clockticks` and check if `perf stat -e clockticks -A`
contains all of them.

Committer testing:

  root@x1:~# grep -m1 "model name" /proc/cpuinfo
  model name	: 13th Gen Intel(R) Core(TM) i7-1365U
  root@x1:~# perf list clockticks

  List of pre-defined events (to be used in -e or -M):

    uncore_clock/clockticks/                           [Kernel PMU event]

  uncore memory:
    unc_m_clockticks
         [Number of clocks. Unit: uncore_imc]
  root@x1:~#
  root@x1:~# perf test uniquifying
   92: perf stat events uniquifying                    : Ok
  root@x1:~# perf test -vv uniquifying
   92: perf stat events uniquifying:
  --- start ---
  test child forked, pid 1552628
  stat event uniquifying test
  ---- end(0) ----
   92: perf stat events uniquifying                    : Ok
  root@x1:~#

Signed-off-by: Chun-Tse Shao <ctshao@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dr. David Alan Gilbert <linux@treblig.org>
Cc: Howard Chu <howardchu95@gmail.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Levi Yun <yeoreum.yun@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Weilin Wang <weilin.wang@intel.com>
Link: https://lore.kernel.org/r/20250513215401.2315949-4-ctshao@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>