Inference: Updates InferencePool Status Management

[danehans]

Description

When an InferencePool was first created, the k8s API server auto-populates one synthetic parent entry. Every time the endpointpicker plugin tried to append the real Gateway parent (or remove it again), the list kept toggling between [default,…] and […].

This PR added stripDefaultParent() and called it in all paths that read/write inferencepool.Status.Parents:

• addGatewayParentRef
• findGatewayParentRef
• removeGatewayParentRef

Fixes #11554

InferencePool status was not being updated when referent/referenced (HTTPRoute and Service) object events were triggered:

• Refactored buildRegisterCallback() to accept the triggering InferencePool status calculation based on HTTPRoute and Service events.
• Expanded InferencePool validation.
• Improved status Logic- referencedGateway() no longer aborts on type assertion failures and continues scanning remaining routes. Removed the GatewayClass check since the GatewayIndex only contains Gateways whose GatewayClass.controllerName matches kgateway. Any Gateway coming out of this index is guaranteed to be managed by kgateway.
• Tests- Added new unit tests covering status edge cases (cross-ns parentRef, wrong kind parentRef, etc.). Updated existing e2e tests to check for expected InferencePool parent status conditions.

Partially Fixes #11379

Change Type

/kind bug_fix
/kind cleanup

Changelog

Endpointpicker plugin: Fixes InferencePool status reconciliation by stripping the synthetic "default" parent entry and patching status when an InferencePool or referent/referenced object event is received.

Additional Notes

• No CRD or API changes.