Change nerdctl snapshotter to overlayfs by default

[dmitrytretyakov]

What type of PR is this?
/kind feature

What this PR does / why we need it:
It changed nerdctl snapshotter from extremely disk space intensive "native" to containerd default "overlayfs".

You can read a very good article about snapshotters here.

In short, your 1GB image with 30 layers (like one of mine) can take 30GB disk space with native snapshotter instead of 1GB with overlayfs

Does this PR introduce a user-facing change?:

"native" snapshotter of nerdctl config is replaced by new var `nerdctl_snapshotter` with default "overlayfs" value

[k8s-ci-robot]

Hi @dmitrytretyakov. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[floryut]

@dmitrytretyakov Thank you for the PR 👍
I had a PR with that a while ago but closed it 😅
It was first reported here containerd/containerd#7054 so all good for me

/ok-to-test

[MrFreezeex]

Thanks :D
/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dmitrytretyakov, floryut, MrFreezeex

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [floryut]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment