image_to_vm.sh: fix flag formatting

Old formatting string resulted in unordered jumbled output.

BUG=None
TEST=./image_to_vm.sh --help

Change-Id: I676c27e75a3b2f59b1171f7c60bbe19500fc6f16
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/3032151
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Tested-by: George Engelbrecht <engeg@google.com>
Commit-Queue: George Engelbrecht <engeg@google.com>
diff --git a/image_to_vm.sh b/image_to_vm.sh
index ce66b94..3625c14 100755
--- a/image_to_vm.sh
+++ b/image_to_vm.sh
@@ -27,8 +27,7 @@
 DEFINE_string disk_layout "2gb-rootfs-updatable" \
   "The disk layout type to use for this image."
 DEFINE_boolean test_image "${FLAGS_FALSE}" \
-  "Acquires image from ${CHROMEOS_TEST_IMAGE_NAME} instead of " \
-  "${CHROMEOS_IMAGE_NAME}."
+  "Use ${CHROMEOS_TEST_IMAGE_NAME} instead of ${CHROMEOS_IMAGE_NAME}."
 DEFINE_string to "" \
   "Destination folder for VM output file(s)"