Bug 1280691: remove old decision tasks and references to them; r=garndt

MozReview-Commit-ID: 3o1nz7sP0j1

--HG--
extra : rebase_source : 7a9c37a2b37806a7ec0bca60b78c6d6d3d236f8a

taskcluster/ci/legacy/tasks/decision/periodic_alder.yml

@@ -1,43 +0,0 @@
-taskId: '{{ "decision task" | as-slugid }}'
-task:
-  created: '{{now}}'
-  deadline: '{{ "1 day" | from-now }}'
-  metadata:
-    source: '{{source}}'
-    owner: '{{owner}}'
-    name: 'Taskcluster decision task for {{project}}'
-    description: |
-      Decision task for testing purposes for alder.
-
-  workerType: gecko-decision
-  provisionerId: aws-provisioner-v1
-
-  scopes:
-    - 'docker-worker:cache:level-{{level}}-{{project}}-tc-vcs-public-sources'
-
-  payload:
-    cache:
-      # The taskcluster-vcs tooling stores the large clone caches in this
-      # directory and will reuse them for new requests this saves about 20s~ and
-      # is the most generic cache possible.
-      level-{{level}}-{{project}}-tc-vcs-public-sources: '/home/worker/.tc-vcs/'
-
-    # Note: This task is built server side without the context or tooling that
-    # exist in tree so we must hard code the version
-    image: 'quay.io/mozilla/decision:0.0.3'
-
-    # Virtually no network or other potentially risky operations happen as part
-    # of the task timeout aside from the initial clone. We intentionally have
-    # set this to a lower value _all_ decision tasks should use a root
-    # repository which is cached.
-    maxRunTime: 1800
-
-    command:
-      - /bin/bash
-      - -c
-      - echo "test: {{comment}} ({{revision}}) for {{owner}}"
-    graphs:
-      - /home/worker/graph.json
-  extra:
-    treeherder:
-      symbol: D

taskcluster/docs/taskgraph.rst

@@ -63,11 +63,10 @@ Decision Task
 The decision task is the first task created when a new graph begins.  It is
 responsible for creating the rest of the task graph.
 
-The decision task for pushes is defined in-tree, currently at
-``testing/taskcluster/tasks/decision``.  The task description invokes ``mach
-taskcluster decision`` with some metadata about the push.  That mach command
-determines the optimized task graph, then calls the TaskCluster API to create
-the tasks.
+The decision task for pushes is defined in-tree, in ``.taskcluster.yml``.  The
+task description invokes ``mach taskcluster decision`` with some metadata about
+the push.  That mach command determines the optimized task graph, then calls
+the TaskCluster API to create the tasks.
 
 Graph Generation
 ----------------