fix: use a container for retry count

[theo-malka]

retry.getMetrics().getNumberOfTotalCalls() methods provide the totalNumber of retries since the application startup while we want to get the retry count for the current context.pipelineTag().uid().
Not sure if using a Map to keep the entries could cause performance issues but it should be OK as we remove entries at the end of the execution.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 91.66667% with 2 lines in your changes missing coverage. Please review.

Project coverage is 80.12%. Comparing base (a69c436) to head (787c5b5).

Files with missing lines	Patch %	Lines
...ine/resilience4j/sink/wrapper/retry/RetrySink.java	91.66%	1 Missing ⚠️
...ine/resilience4j/step/wrapper/retry/RetryStep.java	91.66%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #146      +/-   ##
============================================
- Coverage     80.14%   80.12%   -0.02%     
- Complexity      819      821       +2     
============================================
  Files           156      156              
  Lines          2342     2350       +8     
  Branches        126      126              
============================================
+ Hits           1877     1883       +6     
- Misses          385      387       +2     
  Partials         80       80              

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