Move gdk config setting calls to exist within Gitpod image creation

What does this merge request do and why?

This MR aims to move more logic from https://gitlab.com/gitlab-org/gitlab/-/blob/master/.gitpod.yml and into the Gitpod Docker image creation logic instead. gitlab!105181 (closed) will eventually remove the logic from the .gitpod.yml too.

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.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.