Support staging run for devicelab build+test

This is to fix: https://ci.chromium.org/ui/p/flutter/builders/staging/Linux_build_test%20flutter_gallery__transition_perf/1/overview

Change-Id: I8ed7177908f8ad9f651dd9ffa46121e125ebfe43
Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/33081
Commit-Queue: Keyong Han <keyonghan@google.com>
Reviewed-by: Xilai Zhang <xilaizhang@google.com>
Reviewed-by: Ricardo Amador <ricardoamador@google.com>
Reviewed-by: Yusuf Mohsinally <mohsinally@google.com>
diff --git a/recipes/devicelab/devicelab_drone_build_test.py b/recipes/devicelab/devicelab_drone_build_test.py
index d7790cd..b29afe5 100644
--- a/recipes/devicelab/devicelab_drone_build_test.py
+++ b/recipes/devicelab/devicelab_drone_build_test.py
@@ -89,6 +89,8 @@
 def test(api, task_name, deps, artifact):
   '''Run devicelab test assuming build artifact is available.'''
   git_branch = api.properties.get('git_branch')
+  bucket = api.buildbucket.build.builder.bucket
+  builder_name = 'Linux_android_staging test_drone' if bucket == 'staging' else 'Linux Devicelab Test Drone'
   reqs = []
   # These are dependencies specified in the yaml file. We want to pass them down
   # to test so they also install these dependencies.
@@ -100,7 +102,7 @@
 
   req = api.buildbucket.schedule_request(
       swarming_parent_run_id=api.swarming.task_id,
-      builder='Linux Devicelab Test Drone',
+      builder=builder_name,
       properties=test_props,
       priority=25,
       exe_cipd_version=api.properties.get(