[roll] Roll fuchsia [pkg-resolver] Move concurrent download limit to structured config

Enables hardware-specific customization and tests that depend on the
behavior of the fetch queue to set the value instead of duplicating
the constant.

Original-Fixed: b/303690358
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/927850
Original-Revision: a5ff0d910ccf28441e04e115e2ddcce6b93c8d27
GitOrigin-RevId: 8268cf7e0a6d7fd1e05292fb477d2ce414a6f284
Change-Id: I58eefd5b346c81a60ea6cfbcdafd68fcdddf5ac5

stem

diff --git a/stem b/stem
index 5597689..7078afb 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="396dfebaf751e94650899bcc25b9fe44bc0d0ea9"/>
+             revision="a5ff0d910ccf28441e04e115e2ddcce6b93c8d27"/>
   </projects>
   <hooks>
     <hook name="install-environment"