cache-url: turn off -x by default

I think that generally this is a lot of noise in the logs, as the
internals of cache-url is well tested, so we don't need to trace log
by default.

Change-Id: I25b5a1ec0d8f99691b2b4b62b9fdd537e5a773e4

diskimage_builder/elements/cache-url/bin/cache-url

@@ -15,7 +15,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
+if [ ${DIB_DEBUG_TRACE:-0} -gt 1 ]; then
     set -x
 fi
 set -eu