[updater] make mac builder builderless.

Bug: 1109373
Change-Id: Ia86eb8fd1811948e765a3ceb80acb02de85f76ed
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2368450Reviewed-by: Garrett Beaty <gbeaty@chromium.org>
Commit-Queue: Anjali Doneria <adoneria@google.com>
Cr-Commit-Position: refs/heads/master@{#800701}

infra/config/generated/cr-buildbucket.cfg

@@ -11281,11 +11281,12 @@ buckets {
       name: "mac-omaha-builder-rel"
       swarming_host: "chromium-swarm.appspot.com"
       swarming_tags: "vpython:native-python-wrapper"
-      dimensions: "builder:mac-omaha-builder-rel"
+      dimensions: "builderless:1"
       dimensions: "cores:8"
       dimensions: "cpu:x86-64"
       dimensions: "os:Mac"
       dimensions: "pool:luci.chromium.ci"
+      dimensions: "ssd:0"
       exe {
         cipd_package: "infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build"
         cipd_version: "refs/heads/master"

infra/config/subprojects/chromium/master-only/ci.star

@@ -1623,6 +1623,7 @@ ci.fyi_builder(
     ),
     os = os.MAC_ANY,
     cpu = cpu.X86_64,
+    builderless = True,
 )
 
 ci.fyi_builder(