Remove monkeypatch as now present in upstream

See
https://github.com/abonas/kubeclient/blob/v4.0.0/lib/kubeclient/common.rb#L395

config/initializers/kubeclient.rb

 class Kubeclient::Client
-  # We need to monkey patch this method until
-  # https://github.com/abonas/kubeclient/pull/323 is merged
-  def proxy_url(kind, name, port, namespace = '')
-    discover unless @discovered
-    entity_name_plural =
-      if %w[services pods nodes].include?(kind.to_s)
-        kind.to_s
-      else
-        @entities[kind.to_s].resource_name
-      end
-
-    ns_prefix = build_namespace_prefix(namespace)
-    rest_client["#{ns_prefix}#{entity_name_plural}/#{name}:#{port}/proxy"].url
-  end
-
   # Monkey patch to set `max_redirects: 0`, so that kubeclient
   # does not follow redirects and expose internal services.
   # See https://gitlab.com/gitlab-org/gitlab-ce/issues/53158