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
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Merged revisions 421061 from http://svn.asterisk.org/svn/asterisk/branches/12
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Merged revisions 421062 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@421063 65c4cc65-6c06-0410-ace0-fbb531ad65f3