[release/11.0] Disable WebSocket Clien SendAsync_Cancel_Success test

[rzikm]

Test-only change to clean up CI noise

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🔵 Needs a closer look

Scope the skip to the affected concrete test/configuration to preserve other cancellation coverage.

Pull request overview

Disables a flaky WebSocket cancellation test on release/11.0 to reduce CI noise.

Changes:

• Adds an ActiveIssue skip to SendAsync_Cancel_Success.
• Makes no production-code changes.

File summaries

File	Summary
src/libraries/System.Net.WebSockets.Client/tests/CancelTest.Loopback.cs	Marks the shared loopback cancellation test as an active issue, currently affecting broader configurations than intended.

Review details

Suppressed comments (1)

src/libraries/System.Net.WebSockets.Client/tests/CancelTest.Loopback.cs:75

• The linked issue reports CancelTest_HttpClient_Loopback.SendAsync_Cancel_Success, but placing [ActiveIssue] on this inherited method in CancelTest_Loopback skips the test for every concrete loopback class (SharedHandler, Invoker, HttpClient, and both HTTP/2 variants) and every SSL case. Please scope the skip to the affected concrete test/configuration so the other transport paths retain cancellation coverage.

        [ActiveIssue("https://github.com/dotnet/runtime/issues/132031")]

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Lite

[rzikm]

Test only change => tell mode, approved by Karel

[rzikm]

/ba-g Sockets failure is unrelated