infra: Migrate linux-rel on the CQ to builderfull.

crrev.com/i/3452789 allocates the machines for this.

Bug: 1146481
Change-Id: I0c271016eae64d0e99f205b31efe635cf707cd4f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2576949Reviewed-by: Haiyang Pan <hypan@google.com>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834356}

infra/config/generated/cr-buildbucket.cfg

@@ -34266,12 +34266,11 @@ buckets {
       name: "linux-rel"
       swarming_host: "chromium-swarm.appspot.com"
       swarming_tags: "vpython:native-python-wrapper"
-      dimensions: "builderless:1"
+      dimensions: "builder:linux-rel"
       dimensions: "cores:8"
       dimensions: "cpu:x86-64"
       dimensions: "os:Ubuntu-16.04"
       dimensions: "pool:luci.chromium.try"
-      dimensions: "ssd:0"
       exe {
         cipd_package: "infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build"
         cipd_version: "refs/heads/master"

infra/config/subprojects/chromium/try.star

@@ -1028,6 +1028,7 @@ try_.chromium_linux_builder(
 try_.chromium_linux_builder(
     name = "linux-rel",
     branch_selector = branches.STANDARD_MILESTONE,
+    builderless = not settings.is_master,
     goma_jobs = goma.jobs.J150,
     main_list_view = "try",
     tryjob = try_.job(),