AddAspNetCoreInstrumentation() in metrics setup is duplicative

Hey @samsp-msft, I just noticed we have both AddAspNetCoreInstrumentation() and AddMeter("Microsoft.AspNetCore.Hosting"). I don't think we need AddAspNetCoreInstrumentation() any longer, it only has one http.server.duration metric on it which is already covered by the Hosting Meter.

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* ID: d6316286-f76d-24c0-831a-aabb4796e1f8
* Version Independent ID: 9db87c45-60ba-ce17-118c-f9bd15306ece
* Content: [.NET Observability with OpenTelemetry](https://learn.microsoft.com/en-us/dotnet/core/diagnostics/observability-with-otel#5-configure-opentelemetry-with-the-correct-providers)
* Content Source: [docs/core/diagnostics/observability-with-otel.md](https://github.com/dotnet/docs/blob/main/docs/core/diagnostics/observability-with-otel.md)
* Product: **dotnet-fundamentals**
* GitHub Login: @tommcdon
* Microsoft Alias: **tommcdon**