Dockerfile: do not set JAVA_HOME
Cooja does not require JAVA_HOME after
commit so stop setting JAVA_HOME
in the dockerfile.
@@ -127,7 +127,6 @@ RUN export uid=1000 gid=1000 && \
USER user
# Environment variables
-ENV JAVA_HOME /usr/lib/jvm/java-11-openjdk-i386/
ENV HOME /home/user
ENV CONTIKI_NG ${HOME}/contiki-ng
ENV COOJA ${CONTIKI_NG}/tools/cooja
