Remove syncing Gitaly nodes from chef

What does this MR do?

Part of

• gitlab-com/gl-infra/delivery#1960 (closed)
• https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/15061

This change moves us from syncing Gitaly servers from chef, to just specifying them directly as helm values.

Author Check-list

Please read the Contributing document and once you do, complete the following:

• Assign to the correct reviewer per the contributing document
• Apply the correct metadata per the contributing document
• Link to related MRs for applying the changes on other environments
• Link to related Chef changes
• If necessary link to a Criticality 4 Change Request issue

Reviewer Check-list

• Reviewed the diff jobs to confirm changes are as expected
• No changes shown in the diffs not associated with this MR - This may require a rebase or further investigation

Applier Check-list

• Make sure there is no ongoing deployment for the affected envs before merging (see #announcements slack channel)