perf tests: Speed up metrics checking shell tests

Optimize the execution of the metric validation and metric listing shell
test suites:

1. `stat_metrics_values.sh`:
   The Python metric validator runs the `perf bench futex hash` workload
   for each validated metric relationship. Reduce the benchmark runtime
   limit from `-r 2` (2 seconds) to `-r 1` (1 second). This cuts the
   workload duration in half while still generating sufficient PMU events
   to satisfy non-zero threshold metric validations.

2. `stat_all_metrics.sh`:
   The metric checking test runs `perf stat` sequentially across all
   433+ listed metrics. Change the default workload for system-wide runs
   from `sleep 0.01` to `true`. This avoids the 10ms sleep delay on each
   sequential metric invocation, saving over 4 seconds of total wall
   time during full test suite runs.

Assisted-by: Antigravity:gemini-3.1-pro
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

tools/perf/tests/shell/stat_all_metrics.sh

@@ -7,7 +7,7 @@ ParanoidAndNotRoot()
   [ "$(id -u)" != 0 ] && [ "$(cat /proc/sys/kernel/perf_event_paranoid)" -gt $1 ]
 }
 
-test_prog="sleep 0.01"
+test_prog="true"
 system_wide_flag="-a"
 if ParanoidAndNotRoot 0
 then

tools/perf/tests/shell/stat_metrics_values.sh

@@ -18,7 +18,7 @@ fi
 pythonvalidator=$(dirname $0)/lib/perf_metric_validation.py
 rulefile=$(dirname $0)/lib/perf_metric_validation_rules.json
 tmpdir=$(mktemp -d /tmp/__perf_test.program.XXXXX)
-workload="perf bench futex hash -r 2 -s"
+workload="perf bench futex hash -r 1 -s"
 
 # Add -debug, save data file and full rule file
 echo "Launch python validation script $pythonvalidator"