[recipes] Remove deprecated (ignored) --use-bootstrap flag

This has been ignored for a long time, and I'd like to get rid of it.

R=jchinlee@chromium.org, nodir@chromium.org

Change-Id: I240d59cc10a2882041ac2c8abfeb1894237516a6
Reviewed-on: https://chromium-review.googlesource.com/c/1407425
Reviewed-by: Nodir Turakulov <nodir@chromium.org>
Commit-Queue: Robbie Iannucci <iannucci@chromium.org>

tests/recipes_test.py

@@ -13,8 +13,8 @@ ROOT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 
 def recipes_py(*args):
   subprocess.check_call([
-      os.path.join(ROOT_DIR, 'recipes', 'recipes.py'),
-      '--use-bootstrap'] + list(args))
+      os.path.join(ROOT_DIR, 'recipes', 'recipes.py')
+  ] + list(args))
 
 recipes_py('test', 'run')