Delete MapCounter alternative histogram bucket implementation

[jack-berg]

The exponential histogram aggregation has abstractions that allow you plug in alternative bucket counter implementations. Currently there are two: AdaptingCircularBufferCounter (the default) and MapCounter. MapCounter is only usable in JMH tests (i.e. users can't opt in to using it even with internal APIs), and its considerably slower than AdaptingCircularBufferCounter.

Retaining MapCounter and the abstractions that allow it to be used bloats the codebase and makes the exponential histogram implementation harder to reason about. It was a useful tool for evaluating performance but it served its purpose and its time to remove it.

[codecov]

Codecov Report

Base: 91.25% // Head: 91.27% // Increases project coverage by +0.02% 🎉

Coverage data is based on head (d255987) compared to base (57595b0).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #5047      +/-   ##
============================================
+ Coverage     91.25%   91.27%   +0.02%     
+ Complexity     4894     4866      -28     
============================================
  Files           552      549       -3     
  Lines         14481    14394      -87     
  Branches       1386     1375      -11     
============================================
- Hits          13214    13138      -76     
+ Misses          878      870       -8     
+ Partials        389      386       -3     

Impacted Files	Coverage Δ
...ternal/aggregator/ExponentialHistogramIndexer.java	100.00% <ø> (ø)
...internal/view/ExponentialHistogramAggregation.java	100.00% <ø> (ø)
...rnal/aggregator/AdaptingCircularBufferCounter.java	90.56% <100.00%> (ø)
...rics/internal/aggregator/AdaptingIntegerArray.java	93.75% <100.00%> (ø)
...gregator/DoubleExponentialHistogramAggregator.java	96.66% <100.00%> (-0.14%)	⬇️
.../aggregator/DoubleExponentialHistogramBuckets.java	83.33% <100.00%> (-0.31%)	⬇️
...ava/io/opentelemetry/sdk/internal/RateLimiter.java	100.00% <0.00%> (+5.88%)	⬆️

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