Bug 2139: OSM OCI images have 172.21.1.1 as apt proxy

Removes the apt proxy configuration from the final
image layers

Change-Id: I3f2dfd81a04b42d3ee570cdc71ca41da39e621d0
Signed-off-by: Mark Beierl <mark.beierl@canonical.com>
diff --git a/docker/PLA/Dockerfile b/docker/PLA/Dockerfile
index 282a832..f637362 100644
--- a/docker/PLA/Dockerfile
+++ b/docker/PLA/Dockerfile
@@ -23,18 +23,6 @@
     echo "Acquire::https::Proxy \"$APT_PROXY\";" >> /etc/apt/apt.conf.d/proxy.conf ;\
     fi
 
-ARG APT_PROXY
-RUN if [ ! -z $APT_PROXY ] ; then \
-    echo "Acquire::http::Proxy \"$APT_PROXY\";" > /etc/apt/apt.conf.d/proxy.conf ;\
-    echo "Acquire::https::Proxy \"$APT_PROXY\";" >> /etc/apt/apt.conf.d/proxy.conf ;\
-    fi
-
-ARG APT_PROXY
-RUN if [ ! -z $APT_PROXY ] ; then \
-    echo "Acquire::http::Proxy \"$APT_PROXY\";" > /etc/apt/apt.conf.d/proxy.conf ;\
-    echo "Acquire::https::Proxy \"$APT_PROXY\";" >> /etc/apt/apt.conf.d/proxy.conf ;\
-    fi
-
 RUN DEBIAN_FRONTEND=noninteractive apt-get --yes update && \
     DEBIAN_FRONTEND=noninteractive apt-get --yes install \
     gcc=4:9.3.* \
@@ -76,6 +64,8 @@
     python3-minimal=3.8.* \
     && rm -rf /var/lib/apt/lists/*
 
+RUN rm -f /etc/apt/apt.conf.d/proxy.conf
+
 LABEL authors="Lars-Göran Magnusson"
 
 COPY --from=INSTALL /usr/lib/python3/dist-packages /usr/lib/python3/dist-packages
@@ -102,7 +92,7 @@
 WORKDIR /app/osm_pla
 
 # Changing the security context
-USER appuser 
+USER appuser
 
 ENV OSMPLA_MESSAGE_DRIVER kafka
 ENV OSMPLA_MESSAGE_HOST kafka