Reduce size of GDK base image

What does this merge request do and why?

This reduces the size of the GDK base image (aka. mise-bootstrapped-verify), which in turn reduces the size of the GDK verify image, ultimately making image pulls faster and it more convenient to work with the verify image.

Metric changes

Metric	Before	After
Compressed size	3.93 GB	2.95 GB
Uncompressed size	6.42 GB	5.13 GB
Time to push	146.1s	115.8s
Link	Job #12405786576	Job #12407981599

The build-verify-image job also takes about 100s less to push but this might just be due to intermittent network load. Its actual size on disk will be reduced though.

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 MR references an issue describing the change.
• This change is backward compatible. If not, include steps to communicate to users.
• Tests added for new functionality. If not, raise an issue to follow-up.
• Observability added/updated (logging, metrics, tracing).
• Documentation added/updated.
• Announcement added for notable changes.
• gdk doctor test added.