Turning off internal cert management flag

[ardaguclu]

What would you like to be added:

A flag that is used to turn of internal cert management like in kueue https://github.com/kubernetes-sigs/kueue/blob/main/apis/config/v1beta1/configuration_types.go#L296-L309

Why is this needed:

3rd part tools that tries to provision lws but must rely on their own certificate solution (e.g. cert-manager). Currently, embedded internal cert management blocks this. This already exists in kueue and that would be great if we can have it in lws as well.

Completion requirements:

This enhancement requires the following artifacts:

• Design doc
• API change
• Docs update

The artifacts should be linked in subsequent comments.

[ardaguclu]

JobSet also supports this https://github.com/kubernetes-sigs/jobset/blob/main/api/config/v1alpha1/configuration_types.go#L28