SAR-358 Resolve callback errors

Error in logs, repeatedly:

 device-server Error reason = PROCESS_EVENT_FAILED                                                                                                                                                          
 device-server Desc : Failed to process event                                                                                                                                                               
 device-server Origin : EventCallBack::process_event()                                                                                                                                                      
 device-server Tango exception                                                                                                                                                                              
 device-server Severity = ERROR

When the device starts up a map of Tango proxies are created and stored in a Map here.

The key of this map is the tango FQDN. Initially we set hosts to $.Values.global.tango_host, E.g tango://databaseds-tango-base-test:10000/elt/logger. But what was happening is that the key used was the full k8s hostname, E.g tango://databaseds-tango-base-test.default.svc.cluster.local:10000/mid_d0005/elt/logger. This caused a missed lookup.

The change here is stop using the shorthand hostname, but rather the full one. To enable that, we needed to split $.Values.global.tango_host into hostname and port (in deviceservers.yaml) and then used that to build the required hostname <HOST>.<NAMESPACE>.svc.cluster.local:<PORT>. Template files updated accordingly.

JIRA: SAR-358