Add a new config as sandbox controller mod, which can be either
"podsandbox" or "shim". If empty, set it to default "podsandbox"
when CRI plugin inits.
Signed-off-by: Zhang Tianyang <burning9699@gmail.com>
Rework sandbox monitoring, we should rely on Controller.Wait instead of
CRIService.StartSandboxExitMonitor
Signed-off-by: WangLei <wllenyj@linux.alibaba.com>