util-docker: Ensure all apt update/upgrade/install in one RUN

Prior to this patch those building from these Dockerfiles could
encounter caching issues where the `apt -y update` RUN was loaded from a
cached layer prior to running the `install` command. Typically this was
trying to obtain a package from a wrong IP address. The fix for this is
to run this all in one Docker RUN to avoid loading a broken cache.

Change-Id: If309c5c1d4a0240fed670abe980772d90f7d2172
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/59350
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
12 files changed