Fix BlazorWebAssemblyDiagnosticsEnabled so it can be set from a .csproj

[Copilot]

BlazorWebAssemblyDiagnosticsEnabled and the diagnostics feature switches it drives (MetricsSupport, EventSourceSupport, HttpActivityPropagationSupport) were defaulted in Microsoft.NET.Sdk.BlazorWebAssembly.Current.props. MSBuild imports Sdk.props before the project body, so a value set in a .csproj was read too late — the documented opt-out only worked as a global property (/p:) or from Directory.Build.props.

<!-- Now takes effect: previously ignored because Sdk.props was already evaluated -->
<PropertyGroup>
  <BlazorWebAssemblyDiagnosticsEnabled>false</BlazorWebAssemblyDiagnosticsEnabled>
</PropertyGroup>

Changes

• Moved the diagnostics defaults from Current.props to Current.targets — into the first PropertyGroup, which evaluates at Sdk.targets time (after the project body is read) and before the imported SDK targets initialize the switches to false. The property logic is otherwise unchanged, so the default (all switches true) and the existing /p: opt-out behave as before.
• Extended Build_ResolvesBlazorDiagnosticsFeatureSwitches with cases that set the property in the project body (for both true and false), covering the .csproj path the previous /p:-only test missed.

Notes

• Ordering matters: the block must run before the versioned 6_0/5_0.targets and the Mono WasmFeatures.props that default these switches to false when unset.
• HttpActivityPropagationSupport → System.Net.Http.EnableActivityPropagation mapping lives in the base .NET SDK targets and is unaffected; no extra RuntimeHostConfigurationOption is needed.

• Fixes BlazorWebAssemblyDiagnosticsEnabled cannot be set from a .csproj (conditions evaluated in Sdk.props) #55489

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[Copilot]

Pull request overview

This PR adjusts the Blazor WebAssembly SDK’s MSBuild evaluation order so BlazorWebAssemblyDiagnosticsEnabled (and the derived feature-switch defaults) can be set from within a project file body, not only via global properties.

Changes:

• Moves BlazorWebAssemblyDiagnosticsEnabled and the defaulting logic for MetricsSupport, EventSourceSupport, and HttpActivityPropagationSupport from Microsoft.NET.Sdk.BlazorWebAssembly.Current.props to Microsoft.NET.Sdk.BlazorWebAssembly.Current.targets.
• Extends Build_ResolvesBlazorDiagnosticsFeatureSwitches to validate behavior when BlazorWebAssemblyDiagnosticsEnabled is set inside the .csproj (not just via /p:).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
test/Microsoft.NET.Sdk.BlazorWebAssembly.Tests/VanillaWasmTests.cs	Expands the regression test matrix to cover setting BlazorWebAssemblyDiagnosticsEnabled in the project file body.
src/BlazorWasmSdk/Targets/Microsoft.NET.Sdk.BlazorWebAssembly.Current.targets	Adds targets-time defaults for BlazorWebAssemblyDiagnosticsEnabled and the three derived feature properties so .csproj values are honored.
src/BlazorWasmSdk/Targets/Microsoft.NET.Sdk.BlazorWebAssembly.Current.props	Removes the earlier props-time defaults that prevented .csproj body overrides from taking effect.