Migrate the verify_binaries_codesigned.sh

Migrate script to use flutter conductor.

Validated script works with https://ci.chromium.org/raw/build/logs.chromium.org/flutter/led/fujino_google.com/a963d4974558fee09d4fd5c09821ba1eedec71f8afc31a1f6e84d7b3bcec3274/+/annotations?server=chromium-swarm.appspot.com
(test failure expected as that commit is not codesigned).

Change-Id: I0e4fd98b2bfe85bbcd8dca542641938da39374d8
Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/11620
Reviewed-by: Godofredo Contreras <godofredoc@google.com>
Commit-Queue: Christopher Fujino <fujino@google.com>
diff --git a/recipe_modules/adhoc_validation/resources/verify_binaries_codesigned.sh b/recipe_modules/adhoc_validation/resources/verify_binaries_codesigned.sh
index e185ea3..134ede8 100644
--- a/recipe_modules/adhoc_validation/resources/verify_binaries_codesigned.sh
+++ b/recipe_modules/adhoc_validation/resources/verify_binaries_codesigned.sh
@@ -4,4 +4,4 @@
 
 set -e
 
-dart --enable-asserts ./dev/bots/codesign.dart
+./dev/tools/bin/conductor codesign --verify