[cr-buildbucket.cfg] Increase FYI timeout to 10h (from default 3h)

For the most part FYI builders seem to intentionally run without Goma, and builds
would take about 7h to finish.

Bug: 840631
TBR: tandrii
Change-Id: Ib3ad97c1fd6518a45f969788a7b89bd69c714b56
Reviewed-on: https://chromium-review.googlesource.com/1108345Reviewed-by: Ryan Tseng <hinoka@chromium.org>
Commit-Queue: Ryan Tseng <hinoka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568890}

infra/config/global/cr-buildbucket.cfg

@@ -222,6 +222,7 @@ builder_mixins {
   recipe {
     properties: "mastername:chromium.fyi"
   }
+  execution_timeout_secs: 36000 # 10h
 }
 
 builder_mixins {