Allow WAF to specify cipher list for connection to backend
WAF cipher selection option in the portal is only meant for listener. Usage case example, DHE ciphers are stated to have known issue and are not supported for WAF listener. However, DHE cipher is being used when connecting to backend and occasionally causing 502 error. Due to the need for other connection, we cannot remove DHE (2048) support on the server. It will be good if we can specify WAF's cipher to connect to servers.