Bug 1340564: use an attribute to identify signed tasks; r=Callek

This is a more robust approach than using substring matching on task labels.

As an optimization, this simply avoids creating balrog tasks for unsigned beets
using only-for-attributes, rather than omitting them in a transform.

MozReview-Commit-ID: 8MNOxu0WgXo

taskcluster/taskgraph/transforms/balrog.py

@@ -49,16 +49,6 @@ def validate(config, jobs):
             "In balrog ({!r} kind) task for {!r}:".format(config.kind, label))
 
 
-@transforms.add
-def skip_unsigned_beets(config, jobs):
-    for job in jobs:
-        if ('signing' not in job['dependent-task'].label and
-                'beetmover-repackage' not in job['dependent-task'].label):
-            # Skip making a balrog task for this
-            continue
-        yield job
-
-
 @transforms.add
 def make_task_description(config, jobs):
     for job in jobs: