[roll] Roll fuchsia Revert "[assembly] product_bundle_labels are not built by default"

This reverts commit 9849d1b3c8d3e483c7e55621a3b03f19fb598d8e.

Reason for revert: Broke CI with ninja no-op failure

Original change's description:
> [assembly] product_bundle_labels are not built by default
>
> The //:product_bundles target can now be built without building all
> of the product bundles in the list. This allows us to depend on and
> use product_bundles.json without building all the product bundles.
>
> We do this by generating product_bundles_metadata.json at gn-gen,
> and copying it to product_bundles.json in regenerator.py.
>
> This reduces the build time of multi-product builds by 33%.
>
> Original-Bug: 395937765
> Change-Id: I48fe1e9b06b5fa574595d8f7c796c6a9067dc63d
> Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1207808
> Commit-Queue: Auto-Submit <auto-submit@fuchsia-infra.iam.gserviceaccount.com>
> Reviewed-by: Aaron Wood <aaronwood@google.com>
> Reviewed-by: David Turner <digit@google.com>
> Fuchsia-Auto-Submit: Aidan Wolter <awolter@google.com>

Original-Bug: 395937765
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1209844
Original-Revision: e6f604b2703bb7f98c4212b18001fa259dacd312
GitOrigin-RevId: cb100f92fbc72c657fbb0e4189e21c26a9e2e8b5
Change-Id: I1df3be46f1717eedd61e24dda4cb950e7b4e6dcb
diff --git a/stem b/stem
index 3ce5c52..089ca7c 100644
--- a/stem
+++ b/stem
@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="5758cd882b106ed6cb98f36548cfb3c857d965b9"/>
+             revision="e6f604b2703bb7f98c4212b18001fa259dacd312"/>
   </projects>
   <hooks>
     <hook name="install-environment"