Update grafana dashboards to ray 2.49.2 + add README instructions on how to update

[alanwguo]

Why are these changes needed?

There have been some steady improvements to the grafana dashboards, updating kube-ray's static dashboard configs to have the latest version.

Also adds instructions for the process of updating for future devs.

Related issue number

Checks

• I've made sure the tests are passing.
• Testing Strategy
  • Unit tests
  • Manual tests
  • This PR is not tested :(

[win5923]

Thanks @alanwguo! I think we can wait to merge until the default Ray version is upgraded to 2.49.2 in Kuberay.

Maybe in 1.5.0

[alanwguo]

Thanks @alanwguo! I think we can wait to merge until the default Ray version is upgraded to 2.49.2 in Kuberay.

Maybe in 1.5.0

thanks, sounds good. Is there a place I can track the status of that? Or will someone merge this for me automatically once that's done?

First time contributing to kube-ray.

[win5923]

thanks, sounds good. Is there a place I can track the status of that? Or will someone merge this for me automatically once that's done?

Yes, I’ll ping @Future-Outlier to help with this once we upgrade the default Ray version to 2.49.2.

[ryanaoleary]

LGTM. I was able to test this PR and see the updated dashboards show up correctly:

It'd be really helpful if this PR can be included in KubeRay v1.5.0, because it enables users to view TPU metrics that are now collected in Ray 2.49 in the dashboard, otherwise the panels fail to render: ray-project/ray#57829.

[Future-Outlier]

ray_cluster_active_nodes -> autoscaler_active_nodes
ray_cluster_pending_nodes -> autoscaler_pendinodes
ray_cluster_recently_failed_nodes -> autoscaler_recently_failed_nodes

[Future-Outlier]

Cc @rueian for merge, thank you!