Flip builders on dev instance to use builder_group property.

Bug: 1109276
Change-Id: I8ae88b588b60e3e1c931ed43bf83585ac04a536b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2363548Reviewed-by: Erik Staab <estaab@chromium.org>
Commit-Queue: Garrett Beaty <gbeaty@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799202}

infra/config/dev/subprojects/chromium/ci.star

@@ -37,11 +37,11 @@ luci.recipe.defaults.cipd_package.set(
 
 defaults.bucket.set("ci")
 defaults.build_numbers.set(True)
+defaults.builder_group.set("chromium.dev")
 defaults.builderless.set(None)
 defaults.cpu.set(cpu.X86_64)
 defaults.executable.set(luci.recipe(name = "swarming/staging"))
 defaults.execution_timeout.set(3 * time.hour)
-defaults.mastername.set("chromium.dev")
 defaults.os.set(os.LINUX_DEFAULT)
 defaults.service_account.set(
     "chromium-ci-builder-dev@chops-service-accounts.iam.gserviceaccount.com",

infra/config/generated/cr-buildbucket-dev.cfg

@@ -32,7 +32,7 @@ buckets {
         name: "swarming/staging"
         cipd_package: "infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build"
         cipd_version: "refs/heads/master"
-        properties_j: "mastername:\"chromium.dev\""
+        properties_j: "builder_group:\"chromium.dev\""
       }
       execution_timeout_secs: 10800
       build_numbers: YES
@@ -57,7 +57,7 @@ buckets {
         name: "swarming/staging"
         cipd_package: "infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build"
         cipd_version: "refs/heads/master"
-        properties_j: "mastername:\"chromium.dev\""
+        properties_j: "builder_group:\"chromium.dev\""
       }
       execution_timeout_secs: 10800
       build_numbers: YES
@@ -82,7 +82,7 @@ buckets {
         name: "swarming/staging"
         cipd_package: "infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build"
         cipd_version: "refs/heads/master"
-        properties_j: "mastername:\"chromium.dev\""
+        properties_j: "builder_group:\"chromium.dev\""
       }
       execution_timeout_secs: 10800
       build_numbers: YES
@@ -108,7 +108,7 @@ buckets {
         name: "swarming/staging"
         cipd_package: "infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build"
         cipd_version: "refs/heads/master"
-        properties_j: "mastername:\"chromium.dev\""
+        properties_j: "builder_group:\"chromium.dev\""
       }
       execution_timeout_secs: 10800
       build_numbers: YES
@@ -133,7 +133,7 @@ buckets {
         name: "swarming/staging"
         cipd_package: "infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build"
         cipd_version: "refs/heads/master"
-        properties_j: "mastername:\"chromium.dev\""
+        properties_j: "builder_group:\"chromium.dev\""
       }
       execution_timeout_secs: 10800
       build_numbers: YES
@@ -158,7 +158,7 @@ buckets {
         name: "swarming/staging"
         cipd_package: "infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build"
         cipd_version: "refs/heads/master"
-        properties_j: "mastername:\"chromium.dev\""
+        properties_j: "builder_group:\"chromium.dev\""
       }
       execution_timeout_secs: 10800
       build_numbers: YES
@@ -183,7 +183,7 @@ buckets {
         name: "swarming/staging"
         cipd_package: "infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build"
         cipd_version: "refs/heads/master"
-        properties_j: "mastername:\"chromium.dev\""
+        properties_j: "builder_group:\"chromium.dev\""
       }
       execution_timeout_secs: 10800
       build_numbers: YES