Fix flaky error-result timeout test

[glen-84]

Summary

• RequestExecutorTests.Ensure_Errors_Do_Not_Result_In_Timeouts bounded its execution with new CancellationTokenSource(1000), a wall-clock deadline. On a slow or contended CI runner the 1s timer could fire mid-execution and fold a cancellation error into the result, flipping the snapshot from "Unexpected Execution Error" to "The GraphQL request execution was canceled." and failing the test even though nothing hung.
• Replaced the racy in-test deadline with a framework-level [Fact(Timeout = 30_000)] guard and passed TestContext.Current.CancellationToken, so the test still fails fast on a genuine hang without racing normal-load execution time.

Test plan

• dotnet test on HotChocolate.Execution.Tests, filtered to Ensure_Errors_Do_Not_Result_In_Timeouts — passes.

[Copilot]

Pull request overview

Updates a flaky execution test in HotChocolate.Execution.Tests to avoid racey, wall-clock cancellation that can surface as a spurious “request execution was canceled” error on slow/contended CI.

Changes:

• Replaces the in-test CancellationTokenSource(1000) deadline with an xUnit [Fact(Timeout = 30_000)] timeout guard.
• Passes TestContext.Current.CancellationToken into ExecuteRequestAsync so cancellation is owned by the test framework rather than an arbitrary 1s timer.

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[github-code-quality]

Code Coverage Overview

Languages: C#

C# / code-coverage/dotnet

The overall coverage in the gai/fix-flaky-error-... branch remains at 49%, unchanged from the main branch.

Show a code coverage summary of the most impacted files.

File	main ab96092	gai/fix-flaky-error-... d19e2bf	+/-
/home/runner/wo...erMiddleware.cs	97%	89%	-8%
/home/runner/wo...onMiddleware.cs	94%	88%	-6%
/home/runner/wo...DefaultTopic.cs	89%	90%	+1%
/home/runner/wo...geDispatcher.cs	75%	77%	+2%
/home/runner/wo...PromiseCache.cs	78%	81%	+3%
/home/runner/wo...entsListener.cs	62%	66%	+4%
/home/runner/wo...gerMessage.g.cs	15%	19%	+4%
/home/runner/wo...ewareFactory.cs	95%	100%	+5%
/home/runner/wo...sageRecorder.cs	88%	100%	+12%
/home/runner/wo...tDiagnostics.cs	73%	88%	+15%

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