Bug 1643689 - [taskgraph] enable manifest-scheduling on autoland, r=marco

Sets autoland to use the 'bugbug' test manifest loader. This is being enabled
as part of a temporary trial to see the impact it has on sheriffing.

Differential Revision: https://phabricator.services.mozilla.com/D85011

taskcluster/taskgraph/decision.py

@@ -75,6 +75,7 @@ PER_PROJECT_PARAMETERS = {
     'autoland': {
         'optimize_strategies': 'taskgraph.optimize:project.autoland',
         'target_tasks_method': 'autoland_tasks',
+        'test_manifest_loader': 'bugbug',  # Remove this line to disable "manifest scheduling".
     },
 
     'mozilla-central': {

taskcluster/taskgraph/optimize/__init__.py

@@ -430,7 +430,11 @@ class project(object):
 
     autoland = {
         'test': All(
-            Any('skip-unless-schedules', 'bugbug-reduced-fallback', split_args=split_bugbug_arg),
+            Any(
+                'skip-unless-schedules',
+                'bugbug-reduced-manifests-fallback',
+                split_args=split_bugbug_arg,
+            ),
             'backstop',
         ),
     }

taskcluster/taskgraph/optimize/bugbug.py

@@ -27,6 +27,7 @@ from taskgraph.util.bugbug import (
 @register_strategy("bugbug-reduced-fallback", args=(CT_MEDIUM, True, True, True))
 @register_strategy("bugbug-reduced-high", args=(CT_HIGH, True, True))
 @register_strategy("bugbug-reduced-manifests", args=(CT_MEDIUM, False, True))
+@register_strategy("bugbug-reduced-manifests-fallback", args=(CT_MEDIUM, False, True, True))
 class BugBugPushSchedules(OptimizationStrategy):
     """Query the 'bugbug' service to retrieve relevant tasks and manifests.