cros_setup_toolchains: remove rust-bootstrap from NEW_PACKAGES

this has been built for... a long time. we can remove it now. :)

BUG=None
TEST=CQ

Change-Id: I3fdefa5f458d2b2954734f3ac26518b55333cc8c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2768478
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Stephane Belmon <sbelmon@google.com>
Tested-by: George Burgess <gbiv@chromium.org>
Auto-Submit: George Burgess <gbiv@chromium.org>
Commit-Queue: George Burgess <gbiv@chromium.org>
diff --git a/scripts/cros_setup_toolchains.py b/scripts/cros_setup_toolchains.py
index 71523c3..a96c229 100644
--- a/scripts/cros_setup_toolchains.py
+++ b/scripts/cros_setup_toolchains.py
@@ -82,9 +82,7 @@
 # bot hasn't had a chance to run yet, there are no binary packages available,
 # so we have to list them here and wait.  Once it completes, entries here can
 # be removed so they'll end up on bots & dev's systems.
-NEW_PACKAGES = (
-    'dev-lang/rust-bootstrap',
-)
+NEW_PACKAGES = ()
 
 # Enable the Go compiler for these targets.
 TARGET_GO_ENABLED = (