libct/cg/sd/v2: call initPath from Path
libct/cg/sd/v2: call initPath from Path

Sometimes Path() is called before m.path is initialized (in particular,
this happens from (*linuxContainer).newInitConfig), so we do need to
make sure to call initPath.

This fixes the following integration tests (for cgroup v2 + systemd case,
currently not enabled -- to be enabled by further commits):

 *  runc run (blkio weight)
 * runc run (cgroupv2 mount inside container)

Fixes: ff692f289b6 ("Fix cgroup2 mount for rootless case")
Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

dqminh/runc,dqminh/runc,rhatdan/runc,opencontainers/runc,opencontainers/runc,kolyshkin/runc,kolyshkin/runc,opencontainers/runc,rhatdan/runc,rhatdan/runc,opencontainers/runc,rhatdan/runc,dqminh/runc,kolyshkin/runc,dqminh/runc,kolyshkin/runc