chore: update golang.google.org/grpc dep from v1.71.1 to v1.72.0

[shaneutt]

This updates our golang.google.org/grpc dependency from v1.71.1 to v1.72.0.

This update includes a change that is not backwards compatible for those who were providing their own implementation of the HealthServer interface, as it adds a new List() method to the interface. This is why #722 was failing.

Technically, I don't think Kubernetes calls this List() method anywhere yet, but when I reviewed the proposal for this change I did not see any sign that there was any expectation that it was reasonable to return UNIMPLEMENTED status code for this method like it is for the Watch() method. So as to abide by the specification I went with properly implementing it.

This PR implements the List() method for both the bbr and the epp, but it also adds the distinct ext_proc gRPC service name to the health check (previously, we were just accepting any health check as if it was for the ext_proc service) so that the list method can work as intended and enumerate the named services. I confirmed that Kubernetes handles the SERVICE_UNKNOWN response properly (in fact you can see here that it simply gets mad about any response other than SERVING, and that behavior seems appropriate here).

I made sure to test this locally by building an image, deploying it with an implementation and testing inference requests. Things looked 👍

#722 is no longer needed with this PR, and can be closed.

Release Notes

* bbr and epp gRPC service names are now explicit for health checks (before, you could provide any service name, even one that didn't exist). Health checks in deployments will now need to target the envoy.service.ext_proc.v3.ExternalProcessor service explicitly going forward or health checks will fail.

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[kfswain]

musing: Wondering if this will bite someone later. I dont expect us to have a main dir or file at root. Maybe this is preferred

[shaneutt]

This is the default binary a go build emits, so it was just buggin me because I was building the binaries locally and didn't want it to try and check that in. Wasn't really thinking anyone would actually add this at any point, but if you strongly prefer we don't add this though, no sweat I'll remove it.

[shaneutt]

/label tide/merge-method-rebase

[ahg-g]

what does this represent, would it matter if we remove it?

[ahg-g]

I guess this should match the name in the health check routine, otherwise we return HealthCheckResponse_SERVICE_UNKNOWN.

Wondering why we want to take a dependency on what the service name as defined in https://github.com/envoyproxy/go-control-plane/blob/main/envoy/service/ext_proc/v3/external_processor_grpc.pb.go#L135 when we could control that on our end?

[shaneutt]

To my understanding the gRPC service might not be able to change because ext_proc expects this specific one by name to be present for its requests. At least by default, maybe that's configurable somewhere (on the Envoy side)? In any case, this is the actual service name we've been using since the beginning: if you turn on reflection on the current gRPC server and do a list, this is the exposed service that Envoy is expecting.

[ahg-g]

/lgtm
/approve

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[smarterclayton]

This was reverted in #788 as it caused failures at runtime (see linked issue for details)