[VC-35738] Hide the client-go reflector warning logs

[wallrj]

The aim of this PR is to filter out the warnings logged in client-go/tools/cache/reflector.go when a resource group version is not installed in the Kubernetes API server.
An example of such a warning, with --logging-format=json :

{"caller":"cache/reflector.go:561", "msg":"k8s.io/client-go@v0.31.1/tools/cache/reflector.go:243: failed to list cas-issuer.jetstack.io/v1beta1, Resource=googlecasissuers: the server could not find the requested resource", "ts":1.7320377905120225E12, "v":0}

ℹ️ When --logging-format=json the warning is actually logged as an info message, on stdout.
By default --logging-format=text in which case the warning is logged with a W prefix on stderr.

Hiding the warnings is achieved by creating a filtering logr.LogSink and assigning that to the default klog logger.

However it does not seem possible to maintain the correct file and line numbers when wrapping the logger this way.
I discussed this with the klog authors and they confirm that there are probably bugs in the way the klog functions unwrap the stack:

• https://kubernetes.slack.com/archives/C20HH14P7/p1732035524601449

In that thread on Slack, I learned from the klog authors that there is an in progress PR which will remove this distracting warning message:

• client-go/tools/cache: add APIs with context parameter kubernetes/kubernetes#126387 (review)

So I will close this PR.

[wallrj]

I learned from the klog authors that there is an in progress PR which will remove this distracting warning message:

• client-go/tools/cache: add APIs with context parameter kubernetes/kubernetes#126387 (review)

So I will close this PR.