Fix parent dir retrieval lint

[saschagrunert]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

We now use filepath.Dir to make the gocritic linter happy:

Error: pkg/validate/security_context_linux.go:1582:37: filepathJoin: "../" contains a path separator (gocritic)
    return filepath.Join(cfg.StateDir, "../")

Which issue(s) this PR fixes:

None

Special notes for your reviewer:

cc @rata

Does this PR introduce a user-facing change?

None

[kwilczynski]

/approve /lgtm

[k8s-ci-robot]

@rata: changing LGTM is restricted to collaborators

In response to [this](https://github.com/kubernetes-sigs/cri-tools/pull/1495#pullrequestreview-2179702123): >LGTM, thanks! > >I guess the linter was added after I wrote that? I didn't see it :) Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes-sigs/prow](https://github.com/kubernetes-sigs/prow/issues/new?title=Prow%20issue:) repository.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kwilczynski, rata, saschagrunert

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/kubernetes-sigs/cri-tools/blob/master/OWNERS)~~ [saschagrunert] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[saschagrunert]

LGTM, thanks!

I guess the linter was added after I wrote that? I didn't see it :)

Everything merged all together, so it was not possible to catch that lint in your PR :)