fix: Kafka bootstrap servers cache wasn't implemented correctly

[tippmar-nr]

The Producer and Consumer are both generics, so just using the type name wasn't sufficient; we'll cache on the full Type now instead.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.89%. Comparing base (d57a875) to head (98b9347).

Additional details and impacted files

@@                      Coverage Diff                       @@
##           feature/apm-aws-relationships    #2657   +/-   ##
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  Coverage                          80.89%   80.89%           
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  Files                                459      459           
  Lines                              29102    29102           
  Branches                            3198     3198           
==============================================================
  Hits                               23543    23543           
  Misses                              4767     4767           
  Partials                             792      792           

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