Task 4053, convert unit tests to FAIL/PASS API

[jufajardini]

src/detect-msg.c - Converted statements like "if()... go to end" to the new FAIL/PASS style.

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• I have read the contributing guide lines at https://redmine.openinfosecfoundation.org/projects/suricata/wiki/Contributing
• I have signed the Open Information Security Foundation contribution agreement at https://suricata-ids.org/about/contribution-agreement/
• I have updated the user guide (in doc/userguide/) to reflect the changes made (if applicable)

Link to redmine ticket:
https://redmine.openinfosecfoundation.org/issues/4053

Describe changes:

• in src/detect-msg.c converted the applicable pieces of code to be compatible with the FAIL/PASS API, deleting variables when and if they would be no longer needed after the change.

PRScript output (if applicable):

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