Fix Stopwatch elapsed time conversion

Stopwatch ticks are not TimeSpan ticks when Stopwatch.IsHighResolution
is true (most systems). TimeSpan.FromTicks(stopwatchTicks) produces
incorrect durations. Use Stopwatch.GetElapsedTime() which correctly
handles the frequency conversion.

Author: fdcastel

src/FirebirdSql.Data.FirebirdClient/Metrics/FbMetricsStore.cs

@@ -74,10 +74,9 @@ internal static void CommandStop(long startedAtTicks, FbConnection connection)
 		{
 			if (OperationDuration.Enabled && startedAtTicks > 0)
 			{
-				var elapsedTicks = Stopwatch.GetTimestamp() - startedAtTicks;
-				var elapsedSeconds = TimeSpan.FromTicks(elapsedTicks).TotalSeconds;
+				var elapsed = Stopwatch.GetElapsedTime(startedAtTicks);
 
-				OperationDuration.Record(elapsedSeconds, connection.MetricsConnectionAttributes);
+				OperationDuration.Record(elapsed.TotalSeconds, connection.MetricsConnectionAttributes);
 			}
 		}
 
@@ -87,10 +86,9 @@ internal static void ConnectionOpened(long startedAtTicks, string poolName)
 		{
 			if (ConnectionCreateTime.Enabled && startedAtTicks > 0)
 			{
-				var elapsedTicks = Stopwatch.GetTimestamp() - startedAtTicks;
-				var elapsedSeconds = TimeSpan.FromTicks(elapsedTicks).TotalSeconds;
+				var elapsed = Stopwatch.GetElapsedTime(startedAtTicks);
 
-				ConnectionCreateTime.Record(elapsedSeconds, [new(ConnectionPoolNameAttributeName, poolName)]);
+				ConnectionCreateTime.Record(elapsed.TotalSeconds, [new(ConnectionPoolNameAttributeName, poolName)]);
 			}
 		}