CEL: Update unit tests for additional information

This updates the CEL unit tests for the new information contained in
the attended transfer CEL extra field.
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Merged revisions 420513 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/13@420514 f38db490-d61c-443f-a65b-d21fe96a405b