Re-target the Azure Functions sample to net11.0 once the Functions Worker SDK supports it

## Description

`samples/Sentry.Samples.OpenTelemetry.AzureFunctions` is the one sample still on `net10.0` after the .NET 11 bump in #5529. Everything else moved to `net11.0`.

The Azure Functions Worker SDK has no .NET 11 support yet. Both the pinned `2.0.7` and the current `2.1.0` reject the target framework:

```
Microsoft.Azure.Functions.Worker.Sdk.targets(105,5): error :
Invalid combination of TargetFramework and AzureFunctionsVersion is set.
```

The csproj carries a comment saying as much.

## What to do

Once the Functions Worker SDK supports .NET 11, set the sample's `TargetFramework` to `net11.0` and drop that comment. Nothing else in the repo depends on it - samples deliberately use literal, conventional TFMs rather than the centralized properties, so this is a one-line change.

## Refs

* .NET 11 support: #5527 / #5529

Wait until the Azure Functions Worker SDK supports .NET 11, then inspect the csproj under samples/Sentry.Samples.OpenTelemetry.AzureFunctions. Change its TargetFramework to net11.0, remove the explanatory comment, and build the sample to confirm the SDK accepts the target framework.

Written by the indexing model from the issue text.