Fix pipeline minutes calculation for non-started builds

What does this MR do and why?

Addresses sentry errors: https://new-sentry.gitlab.net/organizations/gitlab/issues/72454/?project=3&referrer=gitlab_integration

When a build is completed but has no duration, the minutes calculation will error out.

Screenshots or screen recordings

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How to set up and validate locally

1. Ensure there's only 1 runner picking up jobs
2. gitlab-ci.yml should be something like

build osx:
  stage: build
  script:
    - echo "a"
  artifacts:
    paths:
      - binaries/

test osx:
  stage: test
  script:
    - echo "b"
  dependencies:
    - build osx
  when: manual

3. When build osx finishes. Remove the job via the UI's delete button on the job
4. Run the manual job test osx - this should fail as it depends on previous job
5. Navigating to pipeline will error out (this MR fixes that)

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.

Related to #404550 (closed)