Migrate away from full system image method port
We have https://gitlab.com/ubports/porting/community-ports/halium-generic-adaptation-build-tools which can be used with Halium 9 ports along with the Halium GSI which makes porting both less time consuming on the build server side but simpler from the port maintainer's POV since there's just two repos (for modified kernel + adaptation overlay for rootfs etc).
This will practically be porting the device starting over again, so care should be taken to ensure there's no new regression compared to the old full systemimage port that's currently used.