helm chart: add container security context

[viktoriaas]

This change adds container security context to admission, controller, scheduler Deployments, and scheduler Job. Container security context is necessary in some restricted environments, e.g. in an environment that employs Restricted Pod Security Standard as default.

This PR is just a cleaner version of #3322

[viktoriaas]

@Monokaix opening a new PR featuring the same commits as before to maintain the history.

[viktoriaas]

/assign @hzxuzhonghu

[Monokaix]

/lgtm

[volcano-sh-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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[lowang-bh]

@viktoriaas please rebase and squash commits to only one.

[volcano-sh-bot]

@viktoriaas: PR needs rebase.

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[Monokaix]

Hi, please rebase your pr: )