Seal Metric class for improved perf (#2461)

src/OpenTelemetry/Metrics/AggregatorStore.cs

@@ -22,7 +22,7 @@ using System.Threading;
 
 namespace OpenTelemetry.Metrics
 {
-    internal class AggregatorStore
+    internal sealed class AggregatorStore
     {
         internal const int MaxMetricPoints = 2000;
         private static readonly ObjectArrayEqualityComparer ObjectArrayComparer = new ObjectArrayEqualityComparer();

src/OpenTelemetry/Metrics/Metric.cs

@@ -20,7 +20,7 @@ using System.Diagnostics.Metrics;
 
 namespace OpenTelemetry.Metrics
 {
-    public class Metric
+    public sealed class Metric
     {
         internal static readonly double[] DefaultHistogramBounds = new double[] { 0, 5, 10, 25, 50, 75, 100, 250, 500, 1000 };
         private AggregatorStore aggStore;