Description

Gauges can be distincted by tags, but process holds old gauge with old tags, after this removed from data source.
This behaviour is fine for counters, but make unuseful metrics values for gauges.

Reproduction Steps

Example source code:

using System.Diagnostics.Metrics;

namespace Test
{
	public class Program
	{
		static Meter s_meter = new Meter("HatCo.HatStore", "1.0.0");

		static IEnumerable<Measurement<int>> m;

		static void Main(string[] args)
		{
			s_meter.CreateObservableGauge<int>("orders-pending", () => m);
			m = new Measurement<int>[]
			{
				new Measurement<int>(1, new KeyValuePair<string,object>("Country", "Italy")),
			};
			Console.WriteLine("Change to Spain");
			Console.ReadLine();

			m = new Measurement<int>[]
			{
				new Measurement<int>(1, new KeyValuePair<string,object>("Country", "Spain")),
			};

			Console.WriteLine("Remove Spain, Update Italy");
			Console.ReadLine();

			m = new Measurement<int>[]
			{
				new Measurement<int>(2, new KeyValuePair<string,object>("Country", "Italy")),
			};

			Console.WriteLine("Press any key to exit");
			Console.ReadLine();
		}
	}
}

Expected behavior

Run example and watch its metrics:
dotnet-counters monitor --name ConsoleApp HatCo.HatStore

After process started metrics is:

[HatCo.HatStore]
    orders-pending
        Country=Italy                                  1

Press enter in example console, this will change metrics from Italy to Spain:

[HatCo.HatStore]
    orders-pending
        Country=Spain                                  1

Here is added Spain and removed Italy.

Press enter in example console, this will change metrics to Italy:

[HatCo.HatStore]
    orders-pending
        Country=Italy                                  2

Now we have updated Italy and removed Spain.

Actual behavior

Run example and watch its metrics:
dotnet-counters monitor --name ConsoleApp HatCo.HatStore

After process started metrics is:

[HatCo.HatStore]
    orders-pending
        Country=Italy                                  1

Press enter in example console, this will change metrics from Italy to Spain:

[HatCo.HatStore]
    orders-pending
        Country=Italy                                  1
        Country=Spain                                  1

Here is added Spain, but removed Italy is remainded.

Press enter in example console, this will change metrics to Italy:

[HatCo.HatStore]
    orders-pending
        Country=Italy                                  2
        Country=Spain                                  1

Now we have update Italy, but remainded Spain.

Regression?

No response

Known Workarounds

Track metrics+tags in own Measurement collection. Return this collection to CreateObservableGauge.
In own collection track missing metrics during update (with respect to metric name, tags, and tags combinations) - set its value to zero.

Configuration

No response

Other information

No response