Memory mode: Adding support for synchronous instruments - Counter

[asafm]

Epic

This is one of many PRs that implement #5105. See the complete plan here.
Specifically, this PR adds the implementation of MemoryMode for the synchronous instrument: counter.

What was done here?

This PR, relative to Exponential and Explicit Histogram PR, is rather trivial. It contains:

• Using a reusable point for returning the result on doAggregateThenMaybeReset for both LongSumAggregator.Handle and DoubleSumAggregator.Handle.
• Adding matching garbage collection benchmark tests
• Adjusting and adding tests for LongSumAggregator and DoubleSumAggregator
• Allowed to set the normalized allocate rate reduction percentage since, for both those aggregations, there was only a single allocation per Attributes, hence the reduction could not reach 99.8 as it did for the previous Exponential and Explicit Histogram aggregations.

[codecov]

Codecov Report

Attention: 27 lines in your changes are missing coverage. Please review.

Comparison is base (f123d78) 90.97% compared to head (e4b856b) 90.94%.

Files	Patch %	Lines
...nal/data/MutableExponentialHistogramPointData.java	12.50%	0 Missing and 14 partials ⚠️
.../metrics/internal/data/MutableDoublePointData.java	14.28%	0 Missing and 6 partials ⚠️
...dk/metrics/internal/data/MutableLongPointData.java	14.28%	0 Missing and 6 partials ⚠️
...ernal/data/MutableExponentialHistogramBuckets.java	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6182      +/-   ##
============================================
- Coverage     90.97%   90.94%   -0.03%     
- Complexity     5670     5672       +2     
============================================
  Files           620      620              
  Lines         16535    16555      +20     
  Branches       1682     1695      +13     
============================================
+ Hits          15042    15056      +14     
+ Misses         1023     1009      -14     
- Partials        470      490      +20     

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[jack-berg]

Couple minor comments, but looks good. Thanks!

[asafm]

@jack-berg pushed all fixes