detect/sip.stat_code: Correct sticky buffer name

[jlucovsky]

Issue: 7295

The sticky buffer name was incorrectly set to method; this commit fixes the name typo with stat_code.

SV_REPO=
SV_BRANCH=OISF/suricata-verify#2072
SU_REPO=
SU_BRANCH=
LIBHTP_REPO=
LIBHTP_BRANCH=

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.09%. Comparing base (c3aa3ae) to head (b5564cf).

Additional details and impacted files

@@              Coverage Diff               @@
##           main-7.0.x   #12145      +/-   ##
==============================================
- Coverage       83.27%   83.09%   -0.18%     
==============================================
  Files             922      922              
  Lines          260794   260794              
==============================================
- Hits           217177   216718     -459     
- Misses          43617    44076     +459     

Flag	Coverage Δ
fuzzcorpus	64.12% <100.00%> (-0.26%)	⬇️
suricata-verify	63.19% <100.00%> (-0.13%)	⬇️
unittests	62.38% <100.00%> (ø)

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[suricata-qa]

Information: QA ran without warnings.

Pipeline 23504