[1.2] libct/cg: add test for remove a non-exist dir in a ro mount point #7027

Job	Run time
cross-i386	38s
test (ubuntu-20.04, 1.22.x, rootless, -race)	6m 58s
test (ubuntu-20.04, 1.22.x, rootless)	6m 52s
test (ubuntu-20.04, 1.22.x, -race)	1m 55s
test (ubuntu-20.04, 1.22.x)	1m 7s
test (ubuntu-20.04, 1.23.x, rootless, -race)	7m 14s
test (ubuntu-20.04, 1.23.x, rootless)	7m 2s
test (ubuntu-20.04, 1.23.x, -race)	1m 59s
test (ubuntu-20.04, 1.23.x)	1m 10s
test (ubuntu-20.04, 1.23.x, criu-dev)	1m 49s
test (ubuntu-24.04, 1.22.x, rootless, -race)	9m 56s
test (ubuntu-24.04, 1.22.x, rootless)	9m 37s
test (ubuntu-24.04, 1.22.x, -race)	2m 51s
test (ubuntu-24.04, 1.22.x)	1m 44s
test (ubuntu-24.04, 1.23.x, rootless, -race)	9m 37s
test (ubuntu-24.04, 1.23.x, rootless)	9m 14s
test (ubuntu-24.04, 1.23.x, -race)	2m 12s
test (ubuntu-24.04, 1.23.x)	1m 40s
test (ubuntu-24.04, 1.23.x, criu-dev)	2m 4s
test (actuated-arm64-6cpu-8gb, 1.23.x, rootless)	11m 32s
test (actuated-arm64-6cpu-8gb, 1.23.x)	1m 19s
all-done	0s
	1h 38m 30s

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