perf tests stat_all_metrics: Change true workload to sleep workload for system wide check

Testcase stat_all_metrics.sh fails in powerpc:

98: perf all metrics test : FAILED!

Logs with verbose:

  [command]# ./perf test 98 -vv
   98: perf all metrics test                                           :
   --- start ---
  test child forked, pid 13262
  Testing BRU_STALL_CPI
  Testing COMPLETION_STALL_CPI
   ----
  Testing TOTAL_LOCAL_NODE_PUMPS_P23
  Metric 'TOTAL_LOCAL_NODE_PUMPS_P23' not printed in:
  Error:
  Invalid event (hv_24x7/PM_PB_LNS_PUMP23,chip=3/) in per-thread mode, enable system wide with '-a'.
  Testing TOTAL_LOCAL_NODE_PUMPS_RETRIES_P01
  Metric 'TOTAL_LOCAL_NODE_PUMPS_RETRIES_P01' not printed in:
  Error:
  Invalid event (hv_24x7/PM_PB_RTY_LNS_PUMP01,chip=3/) in per-thread mode, enable system wide with '-a'.
   ----

Based on above logs, we could see some of the hv-24x7 metric events
fails, and logs suggest to run the metric event with -a option.  This
change happened after the commit a4b8cfcabb ("perf stat: Delay
metric parsing"), which delayed the metric parsing phase and now before
metric parsing phase perf tool identifies, whether target is system-wide
or not. With this change, perf_event_open will fails with workload
monitoring for uncore events as expected.

The perf all metric test case fails as some of the hv-24x7 metric events
may need bigger workload with system wide monitoring to get the data.
Fix this issue by changing current system wide check from true workload
to sleep 0.01 workload.

Result with the patch changes in powerpc:

  98: perf all metrics test : Ok

Fixes: a4b8cfcabb ("perf stat: Delay metric parsing")
Suggested-by: Ian Rogers <irogers@google.com>
Reviewed-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Tested-by: Disha Goel <disgoel@linux.ibm.com>
Tested-by: Ian Rogers <irogers@google.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Nageswara R Sastry <rnsastry@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230215093827.124921-1-kjain@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/shell/stat_all_metrics.sh

@@ -11,7 +11,7 @@ for m in $(perf list --raw-dump metrics); do
     continue
   fi
   # Failed so try system wide.
-  result=$(perf stat -M "$m" -a true 2>&1)
+  result=$(perf stat -M "$m" -a sleep 0.01 2>&1)
   if [[ "$result" =~ "${m:0:50}" ]]
   then
     continue