Simplify and fix 'build yamls' job

To build the yaml files, we only need python3 and make.
All the other/old packages that got installed are needed for building
actual images, so get rid of them.
This should also significantly speed up the job.

While checking the 'artifacts' I noticed that git operations didn't
produce the output as expected, both in top comment as at the end where
build information is written to /etc/raspi-image-id.
That was caused by git not working as it wasn't installed.

debian/salsa-ci.yml

@@ -34,7 +34,7 @@ build yamls:
   dependencies: []
   script:
     - apt-get update && apt-get upgrade -y
-    - eatmydata apt-get install -y vmdb2 dosfstools qemu-utils qemu-user-static debootstrap binfmt-support time kpartx bmap-tools python3 fakemachine make
+    - apt-get install -y python3 make git
     - make yaml
     - mkdir build
     - cp raspi*.yaml build/