Rebuild Gitpod workspace image every 12 hours instead of daily

Overview

There's been times when GDK had been updated, but it will take some time for a Gitpod GDK image (with the "main" tag) to include the GDK changes, because rebuilding a Gitpod GDK image happens daily.

Maybe to start, we should increase the frequency we build Gitpod GDK images to 12 hours from 24 hours. This could motivate team members in other time zones to keep an eye on the scheduled pipeline and release the images.

Impacted categories

The following categories relate to this issue:

• 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.

Ru