Fix TestGetContainerStateAfterUpdate on cgroup v2
Fix TestGetContainerStateAfterUpdate on cgroup v2

CI was failing on cgroup v2 because mockCgroupManager.GetUnifiedPath()
was returning an error.

Now the function returns the value of mockCgroupManager.unifiedPath,
but the value is currently not used in the tests.

Fix #2286

Signed-off-by: Akihiro Suda <10ddef0dea2a66ab193b07198faa879adcb213d8@hco.ntt.co.jp>

mikebrow/runc,estesp/runc,xiaochenshen/runc,rhatdan/runc,mikebrow/runc,rhatdan/runc,kolyshkin/runc,xiaochenshen/runc,rhatdan/runc,opencontainers/runc,dqminh/runc,mikebrow/runc,kolyshkin/runc,estesp/runc,kolyshkin/runc,kolyshkin/runc,rhatdan/runc,dqminh/runc,opencontainers/runc,opencontainers/runc,dqminh/runc,dqminh/runc,estesp/runc,xiaochenshen/runc,opencontainers/runc