Parallelize singleton execution

Bug: 281536768
Test: manual, presubmits
Change-Id: I57fdc76ba6b277e88e196b506af87127a530fd37
diff --git a/android/metrics.go b/android/metrics.go
index 3d41a1d..63c72cd 100644
--- a/android/metrics.go
+++ b/android/metrics.go
@@ -42,7 +42,7 @@
 }
 
 func init() {
-	RegisterSingletonType("soong_metrics", soongMetricsSingletonFactory)
+	RegisterParallelSingletonType("soong_metrics", soongMetricsSingletonFactory)
 }
 
 func soongMetricsSingletonFactory() Singleton { return soongMetricsSingleton{} }