Increase fetch lobs parallelism

16 threads has a miniscule improvement over 8 on the builder but might
allow for more improvements if there's more available cores or bandwidth

Bug: 1260479
Change-Id: Ibd5d35bfad363ddb6a778ff66543009eddd4aa5f
Reviewed-on: https://chromium-review.googlesource.com/c/experimental/website/+/3248168
Reviewed-by: Dirk Pranke <dpranke@google.com>
Commit-Queue: Struan Shrimpton <sshrimp@google.com>

DEPS

diff --git a/DEPS b/DEPS
index abdd172..1d42ca6 100644
--- a/DEPS
+++ b/DEPS
@@ -113,6 +113,7 @@
                 '--bucket', 'dpranke-chromium-website-exp-storage',
                 '-d', 'site',
                 '--recursive',
+                '-t', '16',
     ],
   },
 ]