app_voicemail: Fix leaking config objects when msg_id doesn't match

(issues ASTERISK-22414)
Reported by: Corey Farrell
Patch:
    test_voicemail_api-leaks-11.patch uploaded by coreyfarrell (license 5909)


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/11@398281 f38db490-d61c-443f-a65b-d21fe96a405b
unit tests: test_voicemail_api leaks stringfields from snapshots

(closes issue ASTERISK-22414)
Reported by: Corey Farrell
Patches:
    test_voicemail_api-leaks-11.patch uploaded by coreyfarrell (license 5909)


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/11@398285 f38db490-d61c-443f-a65b-d21fe96a405b