Add device_os dimension for ios-usb-dependencies builder

Change-Id: I65694e8f5edf771f34035a5cc05c0b8cf669a4d2
Bug: https://github.com/flutter/flutter/issues/36019
Reviewed-on: https://flutter-review.googlesource.com/c/infra/+/32821
Reviewed-by: Christopher Fujino <fujino@google.com>
Reviewed-by: Godofredo Contreras <godofredoc@google.com>
Commit-Queue: Keyong Han <keyonghan@google.com>
diff --git a/config/generated/flutter/luci/cr-buildbucket.cfg b/config/generated/flutter/luci/cr-buildbucket.cfg
index e719930..771413a 100644
--- a/config/generated/flutter/luci/cr-buildbucket.cfg
+++ b/config/generated/flutter/luci/cr-buildbucket.cfg
@@ -95601,6 +95601,8 @@
     builders {
       name: "ios-usb-dependencies"
       swarming_host: "chromium-swarm.appspot.com"
+      dimensions: "cpu:x86"
+      dimensions: "device_os:iOS-15"
       dimensions: "os:Mac-12"
       dimensions: "pool:luci.flutter.prod"
       exe {
diff --git a/config/iostools_config.star b/config/iostools_config.star
index 62bc9b2..05a1dcb 100644
--- a/config/iostools_config.star
+++ b/config/iostools_config.star
@@ -58,6 +58,7 @@
         caches = ci_yaml.swarming_caches("flutter", "master"),
         properties = properties,
         os = platform_properties[platform_key]["os"],
+        dimensions = {"device_os": "iOS-15", "cpu": "x86"},
         triggering_policy = scheduler.greedy_batching(
             max_concurrent_invocations = 1,
         ),