Add automation for updating test durations

[mudit2812]

Duplicate of #6247.

• Added a workflow update-durations.yml that uses stored durations artifacts to open a PR containing the updated durations (example workflow run here, example PR here)
  • The workflow will run on a weekly schedule
• Moved durations files to .github/durations folder.
• Change step in tests workflow that uploads stable dependencies to only run if the workflow was triggered by schedule. This change is made to avoid opening a PR for stable dependency updates every time there is a push to master.

[sc-72992]

[github-actions]

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