feat(test): Add integration tests for status server

[digvijay-y]

What this PR does / why we need it:
Adds integration tests for the status server handleTrainJobRuntimeStatus handler.

The tests include coverage of:

• The happy path (updating the train job status)
• invalid data is rejected with a useful error message progressPercentage greater than 100 +kubebuilder:validation:Minimum=0 and +kubebuilder:validation:Maximum=100 with this handler would return 422
• updating a non-existing trainjob is rejected with a useful error message

Which issue(s) this PR fixes (optional, in Fixes #<issue number>, #<issue number>, ... format, will close the issue(s) when PR gets merged):
Fixes #3346

Checklist:

• Docs included if any changes are user facing

[github-actions]

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[Copilot]

Pull request overview

Adds Ginkgo integration coverage for the status server’s handleTrainJobRuntimeStatus endpoint, exercising real API-server validation behavior in the envtest-based integration suite.

Changes:

• Introduces a new integration spec that boots a TLS-enabled status server and posts status updates against it.
• Covers success, invalid payload validation (e.g., progressPercentage > 100), and not-found TrainJob updates.

[Copilot]

The http.Client here has no per-request timeout, and the custom http.Transport will use the default ~30s dial timeout, so a stalled connect can block longer than the Eventually window and slow/hang the suite; set httpClient.Timeout (and/or transport dial/handshake timeouts) to a small value for tests.

[Copilot]

The goroutine running server.Start ignores its returned error, which can turn bind/TLS failures into a later timeout with no useful signal; capture the error via a channel (and fail the spec immediately) so startup issues are surfaced deterministically.