The task_dir successfully cleans when the file is absent

[fengwei0328]

When containerd is stopped, if the shim process has died and it cannot clean up the task's working directory(WORKPATH=/var/lib/containerd/io.containerd.runtime.v2.task/{NS}/${CID}).
restarting containerd will call cleanupAfterDeadShim to start a shim-delete process to clean up the corresponding bundle remnants.
However, if the $WORKPATH/runtime or $WORKPATH/init.pid` is missing, it will report an error and return directly, resulting in cleanup failure. The error message is as follows:

="failed to clean up after shim disconnected" error="io.containerd.runc.v2-rs: IoError { context: \"failed to open file /run/containerd/io.containerd.runtime.v2.task/k8s.io/c120341d22ebda4fbd7306c6f0e50dc2b7a7a2f11fadf501fd83bdc2dd6ed0a4/runtime\", err: Os { code: 2, kind: NotFound, message: \"No such file or directory\" } }\n: exit status 1" id=c120341d22ebda4fbd7306c6f0e50dc2b7a7a2f11fadf501fd83bdc2dd6ed0a4 namespace=k8s.io

On the go-shim side, for the case of the missing init.pid file, it logs the situation and continues with the cleanup operation, ensuring successful cleanup.

https://github.com/containerd/containerd/blob/f0ebbd3c8a662656b458e7e1cca059a690d557a7/cmd/containerd-shim-runc-v2/manager/manager_linux.go#L318-L321

pid, err := runcC.ReadPidFile(filepath.Join(path, process.InitPidFile))
	if err != nil {
		log.G(ctx).WithError(err).Warn("failed to read init pid file")
	}