res_pjsip: Adjust outgoing offer call pref.

res_pjsip: Adjust outgoing offer call pref.

This changes the outgoing offer call preference
default option to match the behavior of previous
versions of Asterisk.

The additional advanced codec negotiation options
have also been removed from the sample configuration
and marked as reserved for future functionality in
XML documentation.

The codec preference options have also been fixed to
enforce local codec configuration.

ASTERISK-29109

Change-Id: Iad19347bd5f3d89900c15ecddfebf5e20950a1c2