Parallelize singleton execution

Bug: 281536768
Test: manual, presubmits
Change-Id: I57fdc76ba6b277e88e196b506af87127a530fd37
diff --git a/apex/key.go b/apex/key.go
index 0a7e80f..3010d76 100644
--- a/apex/key.go
+++ b/apex/key.go
@@ -33,7 +33,7 @@
 
 func registerApexKeyBuildComponents(ctx android.RegistrationContext) {
 	ctx.RegisterModuleType("apex_key", ApexKeyFactory)
-	ctx.RegisterSingletonType("apex_keys_text", apexKeysTextFactory)
+	ctx.RegisterParallelSingletonType("apex_keys_text", apexKeysTextFactory)
 }
 
 type apexKey struct {