ARI: Originate to app local channel subscription code optimization.

Reduce the scope of local_peer and only get it if the ARI originate is
subscribing to the channels.

Review: https://reviewboard.asterisk.org/r/3905/
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Merged revisions 421009 from http://svn.asterisk.org/svn/asterisk/branches/12
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Merged revisions 421010 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@421012 f38db490-d61c-443f-a65b-d21fe96a405b