[roll] Roll fuchsia [rbe][rust] Fixup compare mode command line

rustc_command is no longer defined, switch to its renamed
original_rustc_command.

Original-Bug: 105799
Original-Bug: 106703
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/712302
Original-Revision: 6b43eb4ae003b445a19cb5863d80caae0cbc346b
GitOrigin-RevId: 82030dad9702f829131515961d49356fd2da2076
Change-Id: I5db131c6aea24a1cd9deb291dab8a34328cefa7f

stem

diff --git a/stem b/stem
index 66350d0..1c3e627 100644
--- a/stem
+++ b/stem
@@ -10,7 +10,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="d74e6d02fb2b33349adce548ef4a6415fe04ce70"/>
+             revision="6b43eb4ae003b445a19cb5863d80caae0cbc346b"/>
   </projects>
   <hooks>
     <hook name="install-environment"