Add InstrumentAdvice with histogram bucket boundaries on .NET 9+

Suggest default histogram bucket boundaries for operation duration and
connection create time histograms, improving out-of-the-box resolution.
Guarded by NET9_0_OR_GREATER since InstrumentAdvice is a .NET 9 API.

Author: fdcastel

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

@@ -24,12 +24,20 @@ internal static class FbMetricsStore
 
 		static FbMetricsStore()
 		{
-			// Reference: https://github.com/open-telemetry/semantic-conventions/blob/main/docs/database/database-spans.md
+#if NET9_0_OR_GREATER
+			var durationAdvice = new InstrumentAdvice<double>
+			{
+				HistogramBucketBoundaries = [0.001, 0.005, 0.01, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10],
+			};
+#endif
 
 			OperationDuration = Source.CreateHistogram<double>(
 				"db.client.operation.duration",
 				unit: "s",
 				description: "Duration of database client operations."
+#if NET9_0_OR_GREATER
+				, advice: durationAdvice
+#endif
 			);
 
 			Source.CreateObservableUpDownCounter(
@@ -39,29 +47,20 @@ static FbMetricsStore()
 				description: "The number of connections that are currently in state described by the 'state' attribute."
 			);
 
-			// db.client.connection.idle.max
-			//   The maximum number of idle open connections allowed
-
-			// db.client.connection.idle.min
-			//   The minimum number of idle open connections allowed
-
 			Source.CreateObservableUpDownCounter(
 				"db.client.connection.max",
 				GetConnectionMax,
 				unit: "{connection}",
 				description: "The maximum number of open connections allowed."
 			);
 
-			// db.client.connection.pending_requests
-			//   The number of current pending requests for an open connection
-
-			// db.client.connection.timeouts
-			//   The number of connection timeouts that have occurred trying to obtain a connection from the pool
-
 			ConnectionCreateTime = Source.CreateHistogram<double>(
 				"db.client.connection.create_time",
 				unit: "s",
 				description: "The time it took to create a new connection."
+#if NET9_0_OR_GREATER
+				, advice: durationAdvice
+#endif
 			);
 
 			// db.client.connection.wait_time