Set the pool for branched try builders.

Bug: 922150
Change-Id: Id613a8ac7fe40ada45ce589b61eb3eded89c5b5b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1919498
Auto-Submit: Garrett Beaty <gbeaty@chromium.org>
Reviewed-by: Aaron Gable <agable@chromium.org>
Commit-Queue: Aaron Gable <agable@chromium.org>
Cr-Commit-Position: refs/heads/master@{#715926}

infra/config/generated/cr-buildbucket.cfg

@@ -17009,6 +17009,7 @@ buckets: <
       dimensions: "cores:8"
       dimensions: "cpu:x86-64"
       dimensions: "os:Ubuntu-16.04"
+      dimensions: "pool:luci.chromium.try"
       dimensions: "ssd:0"
       recipe: <
         name: "chromium_trybot"
@@ -17072,6 +17073,7 @@ buckets: <
       dimensions: "cores:8"
       dimensions: "cpu:x86-64"
       dimensions: "os:Ubuntu-16.04"
+      dimensions: "pool:luci.chromium.try"
       dimensions: "ssd:0"
       recipe: <
         name: "chromium_trybot"

infra/config/versioned/branches/beta/buckets/try.star

@@ -3,5 +3,8 @@ vars.bucket.set('try-beta')
 vars.cq_group.set('cq-beta')
 vars.experiment_percentage.set(100)
 
+load('//lib/builders.star', 'defaults')
+defaults.pool.set('luci.chromium.try')
+
 load('//versioned/milestones.star', milestone='beta')
 exec('//versioned/milestones/%s/buckets/try.star' % milestone)

infra/config/versioned/branches/stable/buckets/try.star

@@ -3,5 +3,8 @@ vars.bucket.set('try-stable')
 vars.cq_group.set('cq-stable')
 vars.experiment_percentage.set(100)
 
+load('//lib/builders.star', 'defaults')
+defaults.pool.set('luci.chromium.try')
+
 load('//versioned/milestones.star', milestone='stable')
 exec('//versioned/milestones/%s/buckets/try.star' % milestone)