[1.2] runc delete: fix for rootless cgroup + ro cgroupfs #7029

Job	Run time
cross-i386	42s
test (ubuntu-20.04, 1.22.x, rootless, -race)	7m 17s
test (ubuntu-20.04, 1.22.x, rootless)	6m 55s
test (ubuntu-20.04, 1.22.x, -race)	7m 44s
test (ubuntu-20.04, 1.22.x)	6m 32s
test (ubuntu-20.04, 1.23.x, rootless, -race)	7m 20s
test (ubuntu-20.04, 1.23.x, rootless)	6m 56s
test (ubuntu-20.04, 1.23.x, -race)	7m 49s
test (ubuntu-20.04, 1.23.x)	6m 20s
test (ubuntu-20.04, 1.23.x, criu-dev)	7m 35s
test (ubuntu-24.04, 1.22.x, rootless, -race)	10m 17s
test (ubuntu-24.04, 1.22.x, rootless)	9m 57s
test (ubuntu-24.04, 1.22.x, -race)	8m 23s
test (ubuntu-24.04, 1.22.x)	7m 33s
test (ubuntu-24.04, 1.23.x, rootless, -race)	9m 30s
test (ubuntu-24.04, 1.23.x, rootless)	9m 37s
test (ubuntu-24.04, 1.23.x, -race)	7m 53s
test (ubuntu-24.04, 1.23.x)	6m 22s
test (ubuntu-24.04, 1.23.x, criu-dev)	8m 7s
test (actuated-arm64-6cpu-8gb, 1.23.x, rootless)	11m 28s
test (actuated-arm64-6cpu-8gb, 1.23.x)	7m 30s
all-done	1s
	2h 41m 48s

Provide feedback