detect/siggroup: convert unittests to FAIL/PASS APIs v2

[ghostinthehive]

Previous-PR #6612

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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: #4028

Describe changes:

• Convert unittests SigGroupHeadTest* to use FAIL/PASS APIs
• Cleanup unittests
• Update Copyright year

[codecov]

Codecov Report

Merging #6617 (50b6c0d) into master (244dd11) will decrease coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #6617      +/-   ##
==========================================
- Coverage   77.08%   77.05%   -0.04%     
==========================================
  Files         613      613              
  Lines      186171   186017     -154     
==========================================
- Hits       143519   143343     -176     
- Misses      42652    42674      +22     

Flag	Coverage Δ
fuzzcorpus	52.92% <ø> (-0.06%)	⬇️
suricata-verify	52.15% <ø> (+0.02%)	⬆️
unittests	63.08% <100.00%> (-0.01%)	⬇️

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[jufajardini]

Looks good to me, thanks! :)

[victorjulien]

Merged in #6629, thanks!