dev_status: Exclude shadow buckets

Exclude shadow buckets from evaluation. Shadow buckets are only used
when running tests with led, so we don't really care about whether they
are working or not.

Instead of hardcoding "shadow", use the fact that shadow buckets don't
have any configured builders. This may exclude other buckets as well,
but if those buckets don't have any builders we don't really care.

Bug: b/339638439
Change-Id: I52fb8d55a160fa980de7d88240d6998b84f2ccea
Reviewed-on: https://pigweed-review.googlesource.com/c/infra/recipes/+/209545
Commit-Queue: Rob Mohr <mohrr@google.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Reviewed-by: Ted Pudlik <tpudlik@google.com>
diff --git a/recipes/dev_status.py b/recipes/dev_status.py
index 3901f8d..0bf3d2d 100644
--- a/recipes/dev_status.py
+++ b/recipes/dev_status.py
@@ -67,7 +67,7 @@
 
     status: dict[str, dict[str, api.builder_status.BuilderStatus]] = {}
 
-    bucket_names = set(x.name for x in bb_cfg.buckets)
+    bucket_names = set(x.name for x in bb_cfg.buckets if x.swarming.builders)
 
     with api.step.nest('status'):
         for bucket in bb_cfg.buckets: