Update Gitaly/Praefect to use new format config

What does this MR do and why?

The Gitaly/Praefect Omnibus Config format has changed, and the old version will be unsupported as of v16.
We need to update the image here to use the updated format.

• https://gitlab.com/gitlab-org/gitlab/-/blob/518c82b5a7f5e9e1b077977dcf3daa57dee78e80/doc/update/index.md#praefect-omnibus-gitlab-configuration-structure-change

• https://gitlab.com/gitlab-org/gitlab/-/blob/518c82b5a7f5e9e1b077977dcf3daa57dee78e80/doc/update/index.md#gitaly-omnibus-gitlab-configuration-structure-change

Changes to omnibus are being made in omnibus-gitlab!6867 (merged) to remove support for the old config.

Screenshots or screen recordings

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How to set up and validate locally

Jobs using Gitaly/Praefect should run and not report and deprecated config message during boot.
Jobs of note are be gitaly-cluster, praefect, mtls

MR acceptance checklist

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