sqlclient: remove duplicate db.system settag

Author: johnduhart

src/OpenTelemetry.Instrumentation.SqlClient/Implementation/SqlClientDiagnosticListener.cs

@@ -87,7 +87,6 @@ public override void OnCustom(string name, Activity activity, object payload)
                             _ = this.dataSourceFetcher.TryFetch(connection, out var dataSource);
                             _ = this.commandTextFetcher.TryFetch(command, out var commandText);
 
-                            activity.SetTag(SemanticConventions.AttributeDbSystem, SqlActivitySourceHelper.MicrosoftSqlServerDatabaseSystemName);
                             activity.SetTag(SemanticConventions.AttributeDbName, (string)database);
 
                             this.options.AddConnectionLevelDetailsToActivity((string)dataSource, activity);

src/OpenTelemetry.Instrumentation.SqlClient/Implementation/SqlEventSourceListener.netfx.cs

@@ -143,7 +143,6 @@ private void OnBeginExecute(EventWrittenEventArgs eventData)
 
             if (activity.IsAllDataRequested)
             {
-                activity.SetTag(SemanticConventions.AttributeDbSystem, SqlActivitySourceHelper.MicrosoftSqlServerDatabaseSystemName);
                 activity.SetTag(SemanticConventions.AttributeDbName, databaseName);
 
                 this.options.AddConnectionLevelDetailsToActivity((string)eventData.Payload[1], activity);