Dedup prebuilt mutator registration

Test: m checkbuild
Bug: 146540677
Change-Id: I9f8a11adf61fe6f352ec1eabc7c5bac332348ba2
diff --git a/sdk/testing.go b/sdk/testing.go
index 8aa9be0..e3b8519 100644
--- a/sdk/testing.go
+++ b/sdk/testing.go
@@ -68,13 +68,7 @@
 	ctx.PreArchMutators(android.RegisterVisibilityRuleGatherer)
 	ctx.PostDepsMutators(android.RegisterVisibilityRuleEnforcer)
 
-	ctx.PreArchMutators(func(ctx android.RegisterMutatorsContext) {
-		ctx.BottomUp("prebuilts", android.PrebuiltMutator).Parallel()
-	})
-	ctx.PostDepsMutators(func(ctx android.RegisterMutatorsContext) {
-		ctx.TopDown("prebuilt_select", android.PrebuiltSelectModuleMutator).Parallel()
-		ctx.BottomUp("prebuilt_postdeps", android.PrebuiltPostDepsMutator).Parallel()
-	})
+	android.RegisterPrebuiltMutators(ctx)
 	ctx.RegisterModuleType("package", android.PackageFactory)
 
 	// from java package