[SPARK-37687][K8S] Removes the compile time dependency on the OkHttp http client

[navinvishy]

What changes were proposed in this pull request?

Removes the dependency on the OkHttp http client for the kubernetes client.

Why are the changes needed?

The Kubernetes client supports plugging in different http clients via the Java service provider interface. Since we have a dependency on OkHttp it is not possible to plug in other http clients.

Does this PR introduce any user-facing change?

No

How was this patch tested?

Added a unit test

Was this patch authored or co-authored using generative AI tooling?

No