PT51654939 - RLS is not functional on DNS failure

This issue affected RLS and SAA. To fix this the mapping of a new the
subscription to a handler is now done done no matter if sending of first
SUBSCRIBE message succeeded or not (it may fail at first in case  DNS
is not working at that moment but the stack is able to retry the send
later on).
Merge branch 'PT51654939' into release-4.6