message: [docker] update dep in validator_dynamic build
  Build the dependent base image first in validator_dynamic docker build.
  Closes:
  Approved by: sausagee
diff: @@ -10,4 +10,8 @@ if [ "$https_proxy" ]; then
  PROXY=" --build-arg https_proxy=$https_proxy --build-arg http_proxy=$http_proxy"
  fi
  +# Build validator base image first
  +docker build -f $DIR/../validator/Dockerfile $DIR/../.. --tag libra_e2e --build-arg GIT_REV="$(git rev-parse HEAD)" --build-arg GIT_UPSTREAM="$(git merge-base HEAD origin/master)" --build-arg BUILD_DATE="$(date -u +'%Y-%m-%dT%H:%M:%SZ')" $PROXY "$@"
  +
  +# Build validator_dynamic
  docker build -f $DIR/Dockerfile $DIR/../.. --tag libra_validator_dynamic --build-arg GIT_REV="$(git rev-parse HEAD)" --build-arg GIT_UPSTREAM="$(git merge-base HEAD origin/master)" --build-arg BUILD_DATE="$(date -u +'%Y-%m-%dT%H:%M:%SZ')" $PROXY "$@"
  