roll_util: Don't add "CQ-Do-Not-Cancel-Tryjobs"

Don't add "CQ-Do-Not-Cancel-Tryjobs: true" to rolls. It's now added
automatically by the auto_roller module.

Change-Id: Ic1140868f1883459f367129fd9d9b266fc2061f7
Reviewed-on: https://pigweed-review.googlesource.com/c/infra/recipes/+/36340
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
Reviewed-by: Oliver Newman <olivernewman@google.com>
diff --git a/recipe_modules/roll_util/api.py b/recipe_modules/roll_util/api.py
index 48b3dd7..76d7667 100644
--- a/recipe_modules/roll_util/api.py
+++ b/recipe_modules/roll_util/api.py
@@ -200,7 +200,7 @@
         super(RollUtilApi, self).__init__(*args, **kwargs)
         self.labels_to_set = {x.label: x.value for x in props.labels_to_set}
         self.labels_to_wait_on = props.labels_to_wait_on
-        self.footer = ['CQ-Do-Not-Cancel-Tryjobs: true']
+        self.footer = []
 
     def _single_commit_roll_message(self, roll):
         template = """