MeterListener for http.client.open_connections

### Description

I have updated to .NET 11 RC1 (from the previous preview version), and what I notice is that when I listen to the instrument `http.client.open_connections` a send HTTP requests as before:

```csharp
var httpListener = new MeterListener();
httpListener.InstrumentPublished = (instrument, listener) =>
{
if (instrument.Name == "http.client.open_connections")
{
_tcs = new(TaskCreationOptions.RunContinuationsAsynchronously);
_instrument = instrument;
listener.EnableMeasurementEvents(instrument);
}
};
httpListener.SetMeasurementEventCallback(OnMeasurementRecorded);
httpListener.Start();
```

and the callback:

```csharp
private void OnMeasurementRecorded(
Instrument instrument,
T measurement,
ReadOnlySpan> tags,
object? state) { ... }
```

Then the callback isn't invoked. However, the EnableMeasurementEvents is invoked surely, so the instrument exists.

### Reproduction Steps

See as above

### Expected behavior

The callback invoked.

### Actual behavior

Callback not invoked.

### Regression?

Yes

### Known Workarounds

no

### Configuration

```
dotnet --info
.NET SDK:
Version: 11.0.100-rc.1.26425.128
Commit: 3551975be0
Workload version: 11.0.100-manifests.a6e318ce
MSBuild version: 18.11.0-1.26425.128+3551975be

Runtime Environment:
OS Name: Windows
OS Version: 10.0.26200
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\11.0.100-rc.1.26425.128

.NET workloads installed:
There are no installed workloads to display.
Configured to use workload sets when installing new manifests.
No workload sets are installed. Run "dotnet workload restore" to install a workload set.

Host:
Version: 11.0.0-rc.1.26425.128
Architecture: x64
Commit: 3551975be0

.NET SDKs installed:
10.0.401 [C:\Program Files\dotnet\sdk]
11.0.100-rc.1.26425.128 [C:\Program Files\dotnet\sdk]
```

### Other information

_No response_

Start by running the provided C# reproduction with .NET 11 RC1 and inspect the MeterListener flow through InstrumentPublished and EnableMeasurementEvents for http.client.open_connections. Trace why OnMeasurementRecorded is not reached despite the instrument being enabled. Done means the measurement callback is invoked when HTTP requests are sent.

Written by the indexing model from the issue text.