Use large runner for geo-install job

What does this merge request do and why?

This changes the runner for the geo-install job to saas-linux-large-amd64, which provides double vCPUs and memory, so 8 vCPUs and 32 GB of memory. The geo-install job is currently on the critical path of GDK MR pipelines and we reduce MR pipeline duration by 12 minutes (or 16%) with this change.

See this visualizer link for overview.

See this docs page for available SaaS runners.

How to set up and validate locally

You don’t! 👌

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.