[sdk-metrics] Clean up locking in MetricPoint (#5368)

Author: CodeBlanch

src/OpenTelemetry/Metrics/Base2ExponentialBucketHistogram.cs

@@ -23,8 +23,6 @@ internal sealed partial class Base2ExponentialBucketHistogram
     internal double RunningMax = double.NegativeInfinity;
     internal double SnapshotMax;
 
-    internal int IsCriticalSectionOccupied = 0;
-
     internal ExponentialHistogramData SnapshotExponentialHistogramData = new();
 
     private int scale;

src/OpenTelemetry/Metrics/HistogramBuckets.cs

@@ -27,8 +27,6 @@ public class HistogramBuckets
     internal double RunningMax = double.NegativeInfinity;
     internal double SnapshotMax;
 
-    internal int IsCriticalSectionOccupied = 0;
-
     private readonly BucketLookupNode? bucketLookupTreeRoot;
 
     private readonly Func<double, int> findHistogramBucketIndex;