Remove vault from Brewfile

What does this merge request do and why?

This removes the vault dependency from Brewfile because it is no longer available on Homebrew due to HasiCorp’s decision to change the license of Vault to BUSL. See https://formulae.brew.sh/formula/vault

This is a hotfix to unblock new GDK installations on MacOS, though it will break Vault from starting.

See also this thread (internal) in #gdk.

Relates to #2231 (closed)

How to set up and validate locally

Check the error message of brew reinstall vault. We just can’t install vault anymore.

Impacted categories

The following categories relate to this merge request:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.

Merge request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• Tests added for new functionality. If not, please raise an issue to follow-up.
• Documentation added/updated, if needed.
• Announcement added, if change is notable.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.