Needed for feature 10938: extract_prometheus_scrape_jobs populating prom...

Needed for feature 10938: extract_prometheus_scrape_jobs populating prom template with vnf member, vdur name and kdur name (explained in bug 2077)

This fixes merged patch 10938: this previous patch was causing Helm-based EEs to fail their installation within the extract_prometheus_scrape_jobs method when the element was an NS or VNF

Change-Id: I1007cc7d2d75ef573d160e9420d173b14c1cff51
Signed-off-by: Pedro Escaleira <escaleira@av.it.pt>