main/file: Move test event to emit PLAYBACK event more consistently

This is being done in advance of the test for ASTERISK-23953
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Merged revisions 421059 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 421060 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@421061 f38db490-d61c-443f-a65b-d21fe96a405b