[ASP.NET Core metrics] Discrepancies between spec and implementation

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Describe the bug

**http.server.request.duration**

1) Actual description does not match expected description
**src**:
https://github.com/dotnet/aspnetcore/blob/6e1cebdcb07c3577023f68825b20c60a3692d540/src/Hosting/Hosting/src/Internal/HostingMetrics.cs#L32
**spec**;
https://github.com/open-telemetry/semantic-conventions/blob/main/docs/http/http-metrics.md#metric-httpserverrequestduration:~:text=Duration%20of%20HTTP%20server%20requests

2) Do we need `network.protocol.name`? Spec says recommended only if not `http` by default. `HttpClient` does not report this attribute as well. https://github.com/dotnet/runtime/blob/main/src/libraries/System.Net.Http/src/System/Net/Http/Metrics/MetricsHandler.cs

**src**
https://github.com/dotnet/aspnetcore/blob/6e1cebdcb07c3577023f68825b20c60a3692d540/src/Hosting/Hosting/src/Internal/HostingMetrics.cs#L57

**spec**
https://github.com/open-telemetry/semantic-conventions/blob/main/docs/http/http-metrics.md#metric-httpserverrequestduration

**http.server.active_requests**

1) Actual description does not match expected description as per spec.
**src**:
https://github.com/dotnet/aspnetcore/blob/c379b08edd68e6864b327e486d6e97352841db3a/src/Hosting/Hosting/src/Internal/HostingMetrics.cs#L27

**spec**:
https://github.com/open-telemetry/semantic-conventions/blob/main/docs/http/http-metrics.md#metric-httpserverrequestduration:~:text=Number%20of%20active%20HTTP%20server%20requests.

### Expected Behavior

Metric description matches the spec.

### Steps To Reproduce

_No response_

### Exceptions (if any)

_No response_

### .NET Version

.NET8

### Anything else?

_No response_