ci: drop the canary's temporary branch trigger again

Second end-to-end branch run (31949021363) is green with the revised layout.

No-Verification-Needed: CI-only change (workflow trigger)

Author: maxisbey

.github/workflows/dependency-canary.yml

@@ -51,10 +51,6 @@ on:
         description: "Create/update/close the tracking issue exactly as a scheduled run would"
         type: boolean
         default: false
-  # TEMPORARY while this workflow is under review: exercise it on the PR branch.
-  # Report-only (push runs never touch issues). Remove before merging.
-  push:
-    branches: ["ci/dependency-canary"]
 
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