Use external IP for the servicemanager configuration if available

Use external IP for the servicemanager configuration if available

Servicemanager pre-configuration script modified to use the externalIP address if available. This is useful for the cloud environments where the externalIP address is accessible. As a fallback it uses the internalIP as well which works for the local environments. Also using the InternalIP was the existing behaviour.

Issue-ID: NONRTRIC-1082
Change-Id: I3ad58f41e8ac5eaaaa12a02ab54470bdc62a81d8
Signed-off-by: aravind.est <aravindhan.a@est.tech>