[cinder-csi-plugin] add POSIX shell to docker image

[kayrus]

What this PR does / why we need it:

Which issue this PR fixes(if applicable):
fixes #2875

Special notes for reviewers:

Release note:

[cinder-csi-plugin] add POSIX shell to docker image

[k8s-ci-robot]

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[kayrus]

/cherry-pick release-1.32

[k8s-infra-cherrypick-robot]

@kayrus: once the present PR merges, I will cherry-pick it on top of release-1.32 in a new PR and assign it to you.

In response to this:

/cherry-pick release-1.32

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[kayrus]

/cherry-pick release-1.31

[k8s-infra-cherrypick-robot]

@kayrus: once the present PR merges, I will cherry-pick it on top of release-1.31 in a new PR and assign it to you.

In response to this:

/cherry-pick release-1.31

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[kayrus]

/cherry-pick release-1.30

[k8s-infra-cherrypick-robot]

@kayrus: once the present PR merges, I will cherry-pick it on top of release-1.30 in a new PR and assign it to you.

In response to this:

/cherry-pick release-1.30

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[mnaser]

/lgtm

but I don't think I'm a member of kubernetes org. :)

[k8s-ci-robot]

@mnaser: changing LGTM is restricted to collaborators

In response to this:

/lgtm

but I don't think I'm a member of kubernetes org. :)

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-sigs/prow repository.