Change the default container runtime CRI socket endpoint to the
one of containerd. Previously it was the one for Docker
- Rename constants.DefaultDockerCRISocket to DefaultCRISocket
- Make the constants files include the endpoints for all supported
container runtimes for Unix/Windows.
- Update unit tests related to docker runtime testing.
- In kubelet/flags.go hardcode the legacy docker socket as a check
to allow kubeadm 1.24 to run against kubelet 1.23 if the user
explicitly sets the criSocket field to "npipe:////./pipe/dockershim"
on Windows or "unix:///var/run/dockershim.sock" on Linux.