simplify gitlab ci build script

.gitlab-ci.yml

@@ -10,12 +10,6 @@ stages:
     mkdir -p ~/.docker && echo "$DOCKER_AUTH_CONFIG" >~/.docker/config.json
     export suffix=`expr $CI_COMMIT_TAG ':' '2.4-\(.*\)'`
     docker build --pull \
-      --build-arg HTTP_PROXY=${HTTP_PROXY} \
-      --build-arg HTTPS_PROXY=${HTTPS_PROXY} \
-      --build-arg NO_PROXY=${NO_PROXY} \
-      --build-arg http_proxy=${HTTP_PROXY} \
-      --build-arg https_proxy=${HTTPS_PROXY} \
-      --build-arg no_proxy=${NO_PROXY} \
       -t ubleipzig/symfony-httpd:2.4 \
       -f 2.4/Dockerfile \
       2.4