perf test: Ensure lock contention using pipe mode

The 'kernel lock contention analysis test' requires reliable triggering
of lock contention. On some systems, previous benchmark calls failed to
generate sufficient contention due to low system activity or resource
limits.

This patch adds the -p (pipe) option to all calls of perf bench sched
messaging, ensuring consistent lock contention without relying on
socket-based communication.

Suggested-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Jan Polensky <japo@linux.ibm.com>
Link: https://lore.kernel.org/r/20250725170801.3176678-1-japo@linux.ibm.com


Signed-off-by: Namhyung Kim <namhyung@kernel.org>