Migrate all GitHub build triggers to use deploy keys

data/database.py

@@ -471,6 +471,9 @@ class RepositoryBuildTrigger(BaseModel):
   pull_robot = QuayUserField(allows_robots=True, null=True, related_name='triggerpullrobot',
                              robot_null_delete=True)
 
+  # TODO(jschorr): Remove this column once we verify the backfill has succeeded.
+  used_legacy_github = BooleanField(null=True, default=False)
+
 
 class EmailConfirmation(BaseModel):
   code = CharField(default=random_string_generator(), unique=True, index=True)