mark linux packages autoroller bringup: true (flutter#155705)

Unblock the tree while I investigate
flutter#155704

Author: christopherfujino

.ci.yaml

@@ -388,6 +388,7 @@ targets:
 
   - name: Linux packages_autoroller
     presubmit: false
+    bringup: true # https://github.com/flutter/flutter/issues/155704
     recipe: pub_autoroller/pub_autoroller
     # This takes a while because we need to fetch network dependencies and run
     # Gradle for every android app in the repo