workflows/pr: fix condition for no-pr-failures job (#433097)

    # Do NOT change the name of this job, otherwise the rule will not catch it anymore.

    # This would prevent all PRs from merging.

    name: no PR failures

    if: ${{ cancelled() || failure() }}

    # A single job is "cancelled" when it hits its timeout. This is not the same

    # as "skipped", which happens when the `if` condition doesn't apply.

    # The "cancelled()" function only checks the whole workflow, but not individual

    # jobs.

    if: ${{ failure() || contains(needs.*.result, 'cancelled') }}

    runs-on: ubuntu-24.04-arm

    steps:

      - run: exit 1