app_confbridge: Fix duplicate default_user profile.

* Fixed looking in the wrong profiles container to see if the default_user
profile is already created in verify_default_profiles().  The bridge
profile container is never going to hold user profiles. :)
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Merged revisions 400723 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 400724 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@400728 f38db490-d61c-443f-a65b-d21fe96a405b