GUACAMOLE-623: Remove unnecessary initialization of pwsi.

The pwsi member was previously used to ensure the lws structure was made
available to invocations of the event callback early in the connection
lifecycle such that the underlyin guac_client could always be retrieved.
Since the migration to guac_kubernetes_lws_current_client, this is not
necessary, and isn't supported in older versions of libwebsockets
anyway.

src/protocols/kubernetes/kubernetes.c

@@ -268,7 +268,6 @@ void* guac_kubernetes_client_thread(void* data) {
         .origin = settings->hostname,
         .port = settings->port,
         .protocol = GUAC_KUBERNETES_LWS_PROTOCOL,
-        .pwsi = &kubernetes_client->wsi,
         .userdata = client
     };