Bug 1630708 - Increase the confidence thresholds used by the bugbug-based strategies. r=ahal

Keeping the same for the currently chosen strategy for try auto, since we
don't want to decrease its regression detection rate.

We also add a new shadow scheduler which uses the reduced set with a higher
confidence threshold.

Differential Revision: https://phabricator.services.mozilla.com/D71205

taskcluster/ci/source-test/shadow-scheduler.yml

@@ -88,6 +88,17 @@ bugbug_reduced:
         env:
             TASKGRAPH_OPTIMIZE_STRATEGIES: taskgraph.optimize:experimental.bugbug.reduced
 
+bugbug_reduced_high:
+    description: Runs the bugbug.reduced optimization strategy (with a low confidence threshold) instead of the default.
+    treeherder:
+        symbol: SS(bugbug_reduced_high)
+    index:
+        product: source
+        job-name: shadow-scheduler-bugbug_reduced_high
+    worker:
+        env:
+            TASKGRAPH_OPTIMIZE_STRATEGIES: taskgraph.optimize:experimental.bugbug.reduced_high
+
 seta:
     description: Runs the SETA optimization strategy instead of the default.
     treeherder:

taskcluster/taskgraph/optimize/__init__.py

@@ -423,3 +423,9 @@ class experimental(object):
             'test': Any('skip-unless-schedules', 'bugbug-reduced'),
         }
         """Use the reduced set of tasks (and no groups) chosen by bugbug."""
+
+        reduced_high = {
+            'test': Any('skip-unless-schedules', 'bugbug-reduced-high'),
+        }
+        """Use the reduced set of tasks (and no groups) chosen by bugbug, high
+        confidence threshold."""

taskcluster/taskgraph/optimize/bugbug.py

@@ -36,11 +36,13 @@ class platform(object):
         return not (task.attributes.get('build_type') == "debug")
 
 
-@register_strategy("bugbug-all", args=(platform.all, 0.5))
-@register_strategy("bugbug-all-low", args=(platform.all, 0.3))
-@register_strategy("bugbug-all-high", args=(platform.all, 0.7))
+@register_strategy("bugbug-all", args=(platform.all, 0.7))
+@register_strategy("bugbug-all-low", args=(platform.all, 0.5))
+@register_strategy("bugbug-all-high", args=(platform.all, 0.9))
 @register_strategy("bugbug-debug", args=(platform.debug, 0.5))
+@register_strategy("bugbug-try", args=(platform.debug, 0.5))
 @register_strategy("bugbug-reduced", args=(platform.all, 0.7, True))
+@register_strategy("bugbug-reduced-high", args=(platform.all, 0.9, True))
 class BugBugPushSchedules(OptimizationStrategy):
     """Query the 'bugbug' service to retrieve relevant tasks and manifests.