fix(trainer): preserve local job status in list_jobs

[SahilKumar75]

What this PR does / why we need it:

LocalProcessBackend.list_jobs() currently omits the overall status when constructing each TrainJob. As a result, listed jobs report the default Unknown status even when they are complete, failed, running, or created.

This change calculates each job status using the same logic as get_job() and includes it in the returned TrainJob. It also adds a regression test confirming that a completed local job is listed with the Complete status.

Which issue(s) this PR fixes (optional, in Fixes #<issue number>, #<issue number>, ... format, will close the issue(s) when PR gets merged):

Fixes #703

Checklist:

• Docs are not needed because this corrects existing behavior without changing the public interface

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

[google-oss-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign kramaranya for approval. For more information see the Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[SahilKumar75]

The title has been corrected to the repository format. Could a Kubeflow approver please review this change and add LGTM if it is ready?