PosixSignalRegistrationTests fail on windows x86 Debug

## Build Information
Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1362321
Build error leg or test failing: System.Tests.PosixSignalRegistrationTests.ExternalConsoleManipulation_RegistrationRemoved_UnregisterSucceeds
Pull request: https://github.com/dotnet/runtime/pull/126406

## Error Message

Fill the error message using [step by step known issues guidance](https://github.com/dotnet/arcade/blob/main/Documentation/Projects/Build%20Analysis/KnownIssueJsonStepByStep.md).

```json
{
"ErrorMessage": "System.Tests.PosixSignalRegistrationTests.ExternalConsoleManipulation_RegistrationRemoved_UnregisterSucceeds [FAIL]",
"ErrorPattern": "",
"BuildRetry": true,
"ExcludeConsoleLog": false
}
```

### Known issue validation
**Build: :mag_right:** https://dev.azure.com/dnceng-public/public/_build/results?buildId=1362321
**Error message validated:** `[System.Tests.PosixSignalRegistrationTests.ExternalConsoleManipulation_RegistrationRemoved_UnregisterSucceeds [FAIL]`]
**Result validation:** :white_check_mark: Known issue matched with the provided build.
**Validation performed at:** 4/1/2026 7:40:24 PM UTC

### Report

|Build|Definition|Test|Pull Request|
|---|---|---|---|
|[1362321](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1362321)|dotnet/runtime|[System.Tests.PosixSignalRegistrationTests.ExternalConsoleManipulation_RegistrationRemoved_UnregisterSucceeds](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1362321&view=ms.vss-test-web.build-test-results-tab&runId=38075392&resultId=198908)|dotnet/runtime#126406|
#### Summary
|24-Hour Hit Count|7-Day Hit Count|1-Month Count|
|---|---|---|
|1|1|1|

### Report
#### Summary
|24-Hour Hit Count|7-Day Hit Count|1-Month Count|
|---|---|---|
|0|0|0|