Milo: Move instance configuration to luci-config

milo/appengine/swarming/buildinfo.go

Index: milo/appengine/swarming/buildinfo.go
diff --git a/milo/appengine/swarming/buildinfo.go b/milo/appengine/swarming/buildinfo.go
index c93151697f4a0da807933bf1bbec84e78c7f8ed7..b087f904893e5f17a332c75643a6dadbb7f67afd 100644
--- a/milo/appengine/swarming/buildinfo.go
+++ b/milo/appengine/swarming/buildinfo.go
@@ -37,11 +37,10 @@ type BuildInfoProvider struct {
 }
 
 func (p *BuildInfoProvider) newSwarmingService(c context.Context, host string) (swarmingService, error) {
-	fn := p.swarmingServiceFunc
-	if fn == nil {
-		fn = getSwarmingService
+	if p.swarmingServiceFunc == nil {
+		return newProdService(c, host)
 	}
-	return fn(c, host)
+	return p.swarmingServiceFunc(c, host)
 }
 
 // GetBuildInfo resolves a Milo protobuf Step for a given Swarming task.