Upgrade omnibus-ctl for Ruby 3.2.2 compatibility

Bump omnibus-ctl to version 0.6.12

- Upgrades omnibus-ctl for ruby 3.2.2 compatibility. See
  upstream https://github.com/chef/omnibus-ctl/pull/75/files
- Drop custom omnibus-ctl fork now that upstream supports cinc.

Related https://gitlab.com/gitlab-org/gitlab/-/issues/439021

Changelog: changed

What does this MR do?

Upgrade omnibus-ctl for Ruby 3.2.2 compatibility

Namely https://github.com/chef/omnibus-ctl/pull/75/files

Changes: https://gitlab.com/gitlab-org/build/omnibus-mirror/omnibus-ctl/-/compare/0.6.0.1...v0.6.12?from_project_id=11925685&straight=false

Do we need to apply gitlab-org/build/omnibus-mirror/omnibus-ctl@8f7b82e9 and create 0.6.4.1? It looks like it's something we need to customize. Edited: Updating to v0.6.12 means the patch is already included.

Hopefully fixing gitlab#439021 (closed)

Related issues

Checklist

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