Mention why the upgrade commands are commented.

Config/ProvisionTests/Dockerfiles/opensuse

@@ -7,7 +7,9 @@ ENV PACKAGES="$PACKAGES"
 ARG EXTRA_OPENSUSE
 ENV EXTRA_OPENSUSE="$EXTRA_OPENSUSE"
 
+# Use the image as it comes, do not upgrade it, so that it stays reproducible.
 #RUN zypper -n refresh && zypper -n dist-upgrade -y
+
 RUN zypper -n refresh && zypper -n install -y $PACKAGES $EXTRA_OPENSUSE
 
 COPY bin/main.sh /root/main.sh