removed plugin dir creation as no plugin is installed

cluster/addons/fluentd-elasticsearch/fluentd-es-image/Dockerfile

@@ -38,7 +38,6 @@ RUN BUILD_DEPS="make gcc g++ libc6-dev ruby-dev libffi-dev" \
                      ruby \
     && echo 'gem: --no-document' >> /etc/gemrc \
     && gem install --file Gemfile \
-    && mkdir -p /etc/fluent/plugin \
     && apt-get purge -y --auto-remove \
                      -o APT::AutoRemove::RecommendsImportant=false \
                      $BUILD_DEPS \