Skip flaky BlazorWebView header interception test (dotnet#33928)

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## Description

Skips the flaky
`RequestsCanBeInterceptedAndHeadersAddedForDifferentHosts` BlazorWebView
device test which depends on an external echo service
(`echo.free.beeceptor.com`), making it unreliable in CI.

The test failed on CoreCLR MacCatalyst with `Assert.NotNull() Failure:
Value is null` while passing on Mono MacCatalyst in the same build:
- **Build**:
https://dev.azure.com/dnceng-public/public/_build/results?buildId=1282686&view=ms.vss-test-web.build-test-results-tab&runId=35819496&resultId=100136&paneView=debug

## Issues Fixed

Related dotnet#33927

Author: rmarinho

src/BlazorWebView/tests/DeviceTests/Elements/BlazorWebViewTests.RequestInterception.cs

@@ -154,7 +154,7 @@ public Task RequestsCanBeInterceptedAndCustomDataReturnedForDifferentHosts(strin
 			Assert.Equal("Hello Matthew (param1=value1, param2=value2)", responseObject.message);
 		});
 
-	[Theory]
+	[Theory(Skip = "Flaky due to external service dependency (echo.free.beeceptor.com). See https://github.com/dotnet/maui/issues/33927")]
 #if !ANDROID // Custom schemes are not supported on Android
 #if !WINDOWS // TODO: There seems to be a bug with the implementation in the WASDK version of WebView2
 	[InlineData("app://echoservice/")]