Update EPP to expose metrics to represent ready inference models to serve

[shotarok]

Resolve #598

Update EPP to expose metrics to represent ready inference models to serve. inference_model_ready is a binary metric with the pool_name and model_name labels.

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @shotarok. Thanks for your PR.

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[nirrozenbaum]

/ok-to-test

overall I’m ok with this change. just a heads up - inferencemodel is during some rework and would probably change significantly. not sure if now is a good timing to add metrics.

#892

[shotarok]

@nirrozenbaum Thank you for your review and heads up! I understand InferenceModel may change significantly. If it's better to hold this issue for a future version, I'm happy to close this PR and find the other issue to work on.

[nirrozenbaum]

since @ahg-g is leading the effort on InferenceModel redesign, I will let him comment if he thinks we should make progress with this or wait until things get clearer.

[shotarok]

/retest

[nirrozenbaum]

/test pull-gateway-api-inference-extension-test-e2e-main

[shotarok]

@ahg-g Hello, I understand InferenceModel deprecation is being discussed in "Revisiting The InferenceModel API". Do you think it's worth merging this PR for the versions until InferenceModel is deprecated? If not, I'll close this PR and add a comment on #598, so please let me know. Thanks!

[kfswain]

I'm starting the transition today, so probably okay to hold off.

[shotarok]

@kfswain Thank you for letting me know! Then, I'll close this PR.