Use a datastore batcher for build queries.

milo/appengine/buildbot/builder.go

Index: milo/appengine/buildbot/builder.go
diff --git a/milo/appengine/buildbot/builder.go b/milo/appengine/buildbot/builder.go
index 1231693597466c8f37c7716e72faef2be4c67316..f51d425c2041f385e79cf91269a59ac6a61816bf 100644
--- a/milo/appengine/buildbot/builder.go
+++ b/milo/appengine/buildbot/builder.go
@@ -67,7 +67,7 @@ func getBuilds(
 	}
 	q = q.Order("-number")
 	buildbots := []*buildbotBuild{}
-	err := ds.GetAll(c, q, &buildbots)
+	err := getBuildQueryBatcher(c).GetAll(c, q, &buildbots)
 	if err != nil {
 		return nil, err
 	}