Bug 1824856 - don't run a desktop nightly on-push on oak. r=releng-reviewers,gbrown DONTBUILD

Differential Revision: https://phabricator.services.mozilla.com/D173979

taskcluster/gecko_taskgraph/decision.py

@@ -69,7 +69,7 @@ PER_PROJECT_PARAMETERS = {
         "target_tasks_method": "holly_tasks",
     },
     "oak": {
-        "target_tasks_method": "nightly_desktop",
+        "target_tasks_method": "default",
         "release_type": "nightly-oak",
     },
     "graphics": {