Enable recipe-roller autosubmit

Bug: 773529
Change-Id: If00fae56890e7826f9a08ccafe7d45fff2d31ed0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2015615
Commit-Queue: Stephen Martinis <martiniss@chromium.org>
Reviewed-by: Stephen Martinis <martiniss@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@google.com>
Auto-Submit: Aaron Gable <agable@chromium.org>

infra/config/recipes.cfg

@@ -2,7 +2,8 @@
   "api_version": 2,
   "autoroll_recipe_options": {
     "nontrivial": {
-      "automatic_commit_dry_run": true
+      "automatic_commit_dry_run": true,
+      "set_autosubmit": true
     },
     "trivial": {
       "automatic_commit": true,