In linux platform, the shim server always listens on the socket before
the containerd task manager dial it. It is unlikely that containerd task
manager should handle reconnect because the shim can't restart. For this
case, the containerd task manager should fail fast if there is ENOENT or
ECONNREFUSED error.
And if the socket file is deleted during cleanup the exited task, it
maybe cause that containerd task manager takes long time to reload the
dead shim. For that task.v2 manager, the race case is like:
```
TaskService.Delete
TaskManager.Delete(runtime/v2/manager.go)
shim.delete(runtime/v2/shim.go)
shimv2api.Shutdown(runtime/v2/task/shim.pb.go)
<- containerd has been killed or restarted somehow
bundle.Delete
```
The shimv2api.Shutdown will cause that the shim deletes socket file
(containerd-shim-runc-v2 does). But the bundle is still there. During
reloading, the containerd will wait for the socket file appears again
in 100 seconds. It is not reasonable. The Reconnect should prevent this
case by fast fail.
Closes: #5648.
Fixes: #5597.
Signed-off-by: Wei Fu <fuweid89@gmail.com>
