Update heuristic for container creation time
Update heuristic for container creation time

The file "cgroup.clone_children" is not a part of cgroup v2, so use
"cgroup.events" instead. This heuristic is quite bad, so also check the
cgroup directories to see.

linux-on-ibm-z/cadvisor,linux-on-ibm-z/cadvisor,linux-on-ibm-z/cadvisor