Update cq.cfg to use luci.infra.try bucket instead of luci.infra.depot_tools.try.
Update cq.cfg to use luci.infra.try bucket instead of luci.infra.depot_tools.try.

Buildbucket config changed here:
  https://chromium-review.googlesource.com/c/infra/infra/+/755313 

TBR=phajdan.jr@chromium.org

Bug: 780352
Change-Id: Ie80d578be7d91108c60bbfb59f8184bc237e4408
Reviewed-on: https://chromium-review.googlesource.com/755315
Reviewed-by: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@chromium.org>

CoherentLabs/depot_tools,CoherentLabs/depot_tools