res_pjsip: improve realtime performance #2

The patch removes updating all Endpoints' status on startup.
Instead, only non-qualified aors with static contact
and non-qualified non-expired contacts are retrieved from the realtime to
update the endpoint status to ONLINE.
The endpoint name was added to the contact object to simply find the endpoint
that created this contact.

The status of endpoints with qualified aors will be updated by 'qualify'
functions.

ASTERISK-26061 #close

Change-Id: Id324c1776fa55d3741e0c5457ecac0304cb1a0df