Do not cache bag parent stack until requested

Bag parent stacks are used when inspecting/debugging layouts. Since
they are not needed at runtime when running applications normally,
do not cache bag the parent stack when calling AssetManager::GetBag.

Bug: none
Test: libandroidfw_tests
Change-Id: I29ccdc8ed30d4f2d11ee51ef58f6e459ca6c1f6a
diff --git a/libs/androidfw/AssetManager2.cpp b/libs/androidfw/AssetManager2.cpp
index d349628..c49dc28 100644
--- a/libs/androidfw/AssetManager2.cpp
+++ b/libs/androidfw/AssetManager2.cpp
@@ -1036,9 +1036,7 @@
 
 base::expected<const ResolvedBag*, NullOrIOError> AssetManager2::GetBag(uint32_t resid) const {
   std::vector<uint32_t> found_resids;
-  const auto bag = GetBag(resid, found_resids);
-  cached_bag_resid_stacks_.emplace(resid, found_resids);
-  return bag;
+  return GetBag(resid, found_resids);
 }
 
 base::expected<const ResolvedBag*, NullOrIOError> AssetManager2::GetBag(