Parallelize singleton execution

Bug: 281536768
Test: manual, presubmits
Change-Id: I57fdc76ba6b277e88e196b506af87127a530fd37
diff --git a/java/dexpreopt_bootjars.go b/java/dexpreopt_bootjars.go
index f477f40..116c833 100644
--- a/java/dexpreopt_bootjars.go
+++ b/java/dexpreopt_bootjars.go
@@ -465,7 +465,7 @@
 }
 
 func RegisterDexpreoptBootJarsComponents(ctx android.RegistrationContext) {
-	ctx.RegisterSingletonModuleType("dex_bootjars", dexpreoptBootJarsFactory)
+	ctx.RegisterParallelSingletonModuleType("dex_bootjars", dexpreoptBootJarsFactory)
 }
 
 func SkipDexpreoptBootJars(ctx android.PathContext) bool {