Remove Golang version 1.20.4

What does this merge request do and why?

This MR removes Golang version 1.20.4 since GITLAB_SHELL_VERSION has been updated, and the new version of gitlab-org/gitlab-shell no longer requires this version.

I removed Node.js and Vale versions from .tool-versions-gdk file because they are now the default versions.

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.