Remove MutatorHandle.Parallel()

All mutators are parallel by default, remove the explicit Parallel()
calls.

Bug: 372540665
Test: all soong tests pass
Flag: EXEMPT refactor
Change-Id: I41e3a71bd13c75b7fceae91b1c4cfe678ab62df2
diff --git a/apex/apex.go b/apex/apex.go
index 6bb2a1a..30b16ee 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -55,20 +55,20 @@
 }
 
 func RegisterPreDepsMutators(ctx android.RegisterMutatorsContext) {
-	ctx.BottomUp("apex_vndk_deps", apexVndkDepsMutator).Parallel().UsesReverseDependencies()
+	ctx.BottomUp("apex_vndk_deps", apexVndkDepsMutator).UsesReverseDependencies()
 }
 
 func RegisterPostDepsMutators(ctx android.RegisterMutatorsContext) {
-	ctx.TopDown("apex_info", apexInfoMutator).Parallel()
-	ctx.BottomUp("apex_unique", apexUniqueVariationsMutator).Parallel()
-	ctx.BottomUp("apex_test_for_deps", apexTestForDepsMutator).Parallel()
-	ctx.BottomUp("apex_test_for", apexTestForMutator).Parallel()
+	ctx.TopDown("apex_info", apexInfoMutator)
+	ctx.BottomUp("apex_unique", apexUniqueVariationsMutator)
+	ctx.BottomUp("apex_test_for_deps", apexTestForDepsMutator)
+	ctx.BottomUp("apex_test_for", apexTestForMutator)
 	// Run mark_platform_availability before the apexMutator as the apexMutator needs to know whether
 	// it should create a platform variant.
-	ctx.BottomUp("mark_platform_availability", markPlatformAvailability).Parallel()
+	ctx.BottomUp("mark_platform_availability", markPlatformAvailability)
 	ctx.Transition("apex", &apexTransitionMutator{})
-	ctx.BottomUp("apex_directly_in_any", apexDirectlyInAnyMutator).Parallel().MutatesDependencies()
-	ctx.BottomUp("apex_dcla_deps", apexDCLADepsMutator).Parallel()
+	ctx.BottomUp("apex_directly_in_any", apexDirectlyInAnyMutator).MutatesDependencies()
+	ctx.BottomUp("apex_dcla_deps", apexDCLADepsMutator)
 }
 
 type apexBundleProperties struct {