kafka filter support sync producer and message key

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 50.00000% with 34 lines in your changes are missing coverage. Please review.

Project coverage is 79.55%. Comparing base (051079d) to head (9faa384).
Report is 1 commits behind head on main.

Files	Patch %	Lines
pkg/filters/kafkabackend/kafka.go	50.00%	27 Missing and 7 partials ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1239      +/-   ##
==========================================
- Coverage   79.63%   79.55%   -0.09%     
==========================================
  Files         152      152              
  Lines       17228    17281      +53     
==========================================
+ Hits        13720    13748      +28     
- Misses       2845     2866      +21     
- Partials      663      667       +4     

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