fix: error in Kubelet when using default root directory

[fappy1234567]

Relevant Issue

Fixes #288

Details

Setting the snapshotter's default root path to /var/lib/containerd/io.containerd.snapshotter.v1.nydus can resolve the issue.

[imeoer]

Thanks for the PR! but it seems the string /var/lib/containerd-nydus is across multiple files, can we correct them all?

[fappy1234567]

@imeoer Thank you for your feedback and review! I have checked and updated the string /var/lib/containerd-nydus across all relevant files, except for two yaml files in the \tests\e2e\k8s directory. Please review the changes and let me know if there's anything else that needs to be adjusted.

[imeoer]

@fappy1234567 Thanks, I think there's no reason to keep tests/e2e/k8s, and the README.md needs also to be updated. :)

[fappy1234567]

@imeoer I've already updated the README.md. Let me know if there's anything else that needs attention.

[imeoer]

@fappy1234567 Thanks, the tests/e2e/k8s also need to be updated.

[fappy1234567]

@imeoer Thank you for your guidance. I have also updated the tests/e2e/k8s section, but there are some checks that are not passing. When you have a moment, could you please take a look and see if there is anything that needs to be adjusted? Thank you very much!

[imeoer]

LGTM, thanks!