remove unused code (Azure#37470)

sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Tests/AzureMonitorExporterEventSourceTests.cs

@@ -1,9 +1,6 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
-using System;
-using System.Collections.Generic;
-using System.Diagnostics.Tracing;
 using Azure.Monitor.OpenTelemetry.Exporter.Internals.Diagnostics;
 using Azure.Monitor.OpenTelemetry.Exporter.Tests.CommonTestFramework;
 using Xunit;
@@ -24,48 +21,5 @@ public void EventSourceTest_AzureMonitorExporterEventSource()
         {
             EventSourceTestHelper.MethodsAreImplementedConsistentlyWithTheirAttributes(AzureMonitorExporterEventSource.Log);
         }
-
-        public class TestListener : EventListener
-        {
-            private readonly List<EventSource> eventSources = new();
-            private readonly Guid guid = Guid.NewGuid();
-
-            public List<EventWrittenEventArgs> Events = new();
-
-            public TestListener()
-            {
-                EventSource.SetCurrentThreadActivityId(guid);
-            }
-
-            public override void Dispose()
-            {
-                foreach (EventSource eventSource in this.eventSources)
-                {
-                    this.DisableEvents(eventSource);
-                }
-
-                base.Dispose();
-                GC.SuppressFinalize(this);
-            }
-
-            protected override void OnEventSourceCreated(EventSource eventSource)
-            {
-                if (eventSource.Name == AzureMonitorExporterEventSource.EventSourceName)
-                {
-                    this.eventSources.Add(eventSource);
-                    this.EnableEvents(eventSource, EventLevel.Verbose, EventKeywords.All);
-                }
-
-                base.OnEventSourceCreated(eventSource);
-            }
-
-            protected override void OnEventWritten(EventWrittenEventArgs eventData)
-            {
-                if (eventData.ActivityId == this.guid)
-                {
-                    this.Events.Add(eventData);
-                }
-            }
-        }
     }
 }