hs-test: exit immediately if docker build fails

Type: test

Change-Id: I299d023ce59b931697352c54e4796ba0af2ab1af
Signed-off-by: Adrian Villin <avillin@cisco.com>

extras/hs-test/script/build_hst.sh

@@ -69,7 +69,7 @@ fi
 docker_build () {
     tag=$1
     dockername=$2
-    set -x
+    set -ex
     # shellcheck disable=2086
     docker buildx build ${DOCKER_CACHE_ARGS}  \
       --build-arg UBUNTU_VERSION              \
@@ -78,7 +78,7 @@ docker_build () {
       --build-arg HTTP_PROXY="$HTTP_PROXY"    \
       --build-arg HTTPS_PROXY="$HTTP_PROXY"   \
       -t "$tag" -f docker/Dockerfile."$dockername" .
-    set +x
+    set +ex
 }
 
 docker_build hs-test/vpp vpp