chore(api): Remove duplicate TrainJob status patch

[robert-bell]

What this PR does / why we need it:

Small refactoring to tidy up the implementation from #3258.

• Removes duplicate code for updating the TrainJob status in the reconciliation loop to simplify maintenance.
• Changed reconcileDeadline to return ctrl.Result instead of (ctrl.Result, error) since it never returned non-nil errors.

Checklist:

• Docs included if any changes are user facing

[google-oss-prow]

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[Copilot]

Pull request overview

Refactors the TrainJob reconciliation loop to remove duplicated status-patching logic introduced in #3258, and simplifies reconcileDeadline since it never returns an error.

Changes:

• Consolidates TrainJob status patching into a single location in Reconcile.
• Changes reconcileDeadline signature to return only ctrl.Result.
• Adjusts deadline-based requeue handling to reuse the unified status patch logic.

[Copilot]

The DeepEqual call compares &trainJob.Status (a pointer) with prevTrainJob.Status (a value), which will always evaluate as different and cause a status patch on every reconcile; compare like-for-like (either both values or both pointers) to avoid unnecessary API writes and update conflicts.

Suggested change

	if !equality.Semantic.DeepEqual(&trainJob.Status, prevTrainJob.Status) {
	if !equality.Semantic.DeepEqual(trainJob.Status, prevTrainJob.Status) {

[XploY04]

@robert-bell I think it would be great if you fix this in this PR as well.

[robert-bell]

Updated.

cc @astefanutti @andreyvelich - I think this came up before in #3227 but we reverted the change that time. Just flagging in case you wanted to comment.

I think we should make this change though - testing locally, the current logic is always returning false so we're making a status patch on every reconcile regardless of whether the status has changed.

[robert-bell]

cc @XploY04 - this is a small tidy up from your PR #3258. ptal

[robert-bell]

Thanks for the review @XploY04. PTAL.

I've also rebased which should hopefully fix the ci e2e tests.