Users should be able to customize the transport service

[barkbay]

#2543 introduced a transport service to let Elasticsearch nodes communicate to remote Elasticsearch clusters.

A user should be able to control the spec of this service like we do for the HTTP service (e.g. set the type to LoadBalancer)

[pebrc]

I assume something like this will work:

transport:
   service:
      metadata:
      spec: 

Mirroring the format we use for the http side but leaving out the tls options as we cannot offer TLS configuration on the transport layer (yet)