remove duplicate FQDNs in peer roles

Bug: 951283
Change-Id: I4d43bc8860dbeff47568232f72a4910890ca004d
skip unknown FQDNs in peer roles, instead of using 'None'

Bug: 952948
Change-Id: I296e74633b08cb12af5f100cd1b4c428d9534bc1
Merge changes I296e7463,I4d43bc88 into release-0.12

* changes:
  skip unknown FQDNs in peer roles, instead of using 'None'
  remove duplicate FQDNs in peer roles