mqtt: Improve handling of multiple PDU parsing

[jlucovsky]

Continuation of #10279

Issue: 6592

Link to redmine ticket: 6592

Describe changes:

• Parse PDU instead of entire stream

Updates:

• Remove debug prints added during fix

Provide values to any of the below to override the defaults.

To use a pull request use a branch name like pr/N where N is the
pull request number.

Alternatively, SV_BRANCH may also be a link to an
OISF/suricata-verify pull-request.

SV_REPO=
SV_BRANCH=pr/1609
SU_REPO=
SU_BRANCH=
LIBHTP_REPO=
LIBHTP_BRANCH=

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (244a35d) 73.31% compared to head (5c683c7) 82.33%.

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #10305       +/-   ##
===========================================
+ Coverage   73.31%   82.33%    +9.02%     
===========================================
  Files         895      978       +83     
  Lines      148215   272029   +123814     
===========================================
+ Hits       108666   223981   +115315     
- Misses      39549    48048     +8499     

Flag	Coverage Δ
fuzzcorpus	63.58% <100.00%> (+0.10%)	⬆️
suricata-verify	61.49% <100.00%> (-0.04%)	⬇️
unittests	62.84% <0.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

[catenacyber]

Code looks good to me.

Commit message should mention "frames" ;-)

[jlucovsky]

Continued in #10309