sys/linux/test: add a seed enabling PMU #14858

Job	Run time
dashboard	3m 29s
build	11m 18s
aux	5m 7s
race_dashboard	4m 35s
race	8m 4s
arch (presubmit_arch_linux)	10m 52s
arch (presubmit_arch_freebsd)	6m 32s
gvisor	4m 14s
arch (presubmit_arch_netbsd)	4m 34s
old	6m 34s
arch (presubmit_arch_openbsd)	4m 28s
arch (presubmit_arch_darwin)	4m 31s
arch (presubmit_arch_windows)	3m 30s
arch (presubmit_arch_executor)	3m 22s
	1h 21m 10s

Provide feedback