Remove redundant commands

.. see #2420 (comment)

As suggested by @polarathene the not needed repos are more elegantly removed,
commands for removing util-linux removal and zypper up were redudant and thus
squashed.

First stage was build manually and it looked fine.

This fixes #2439 .

Author: drwetter

Dockerfile

@@ -10,16 +10,13 @@ ARG INSTALL_ROOT
 
 # /etc/os-release provides $VERSION_ID below.
 # We don't need the openh264.repo and the non-oss repos, just costs build time (repo caches).
-# Also we need to remove the util_linux RPM to /really/ make sure busybox-util-linux gets installed.
-# And we need to run zypper update, see all PR #2424.
+
 RUN source /etc/os-release \
-  && rm -f /etc/zypp/repos.d/repo-openh264.repo /etc/zypp/repos.d/repo-non-oss.repo \
+  && zypper removerepo repo-openh264 repo-non-oss repo-update-non-oss \
   && export ZYPPER_OPTIONS=( --releasever "${VERSION_ID}" --installroot "${INSTALL_ROOT}" --cache-dir "${CACHE_ZYPPER}" ) \
   && zypper "${ZYPPER_OPTIONS[@]}" --gpg-auto-import-keys refresh \
-  && rpm -e util-linux --nodeps \
   && zypper "${ZYPPER_OPTIONS[@]}" --non-interactive install --download-in-advance --no-recommends \
        bash procps grep gawk sed coreutils busybox ldns libidn2-0 socat openssl curl \
-  && zypper up -y \
   && zypper "${ZYPPER_OPTIONS[@]}" clean --all
 ## Cleanup (reclaim approx 13 MiB):
 # None of this content should be relevant to the container: