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/android/path_properties.go b/android/path_properties.go
index 6210aee..d80a8ed 100644
--- a/android/path_properties.go
+++ b/android/path_properties.go
@@ -27,7 +27,7 @@
 // to the output file of the referenced module.
 
 func registerPathDepsMutator(ctx RegisterMutatorsContext) {
-	ctx.BottomUp("pathdeps", pathDepsMutator).Parallel()
+	ctx.BottomUp("pathdeps", pathDepsMutator)
 }
 
 // The pathDepsMutator automatically adds dependencies on any module that is listed with the