EXC_BAD_INSTRUCTION in System.ValueTuple.Tests on tvos

## Build Information
Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1519006
Build error leg or test failing: System.Runtime.Tests.WorkItemExecution
Pull request: https://github.com/dotnet/runtime/pull/131126

## Error Message

**DO NOT USE JSON BELOW IF THIS IS A BUILD BREAK** otherwise build analysis will allow pull requests to merge that break the build worse. For a build break, do not use this issue form. Make a regular new issue.

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

```json
{
"ErrorMessage": ["System.ValueTuple.Tests", "EXC_BAD_INSTRUCTION"],
"BuildRetry": false,
"ExcludeConsoleLog": false
}
```

### Known issue validation
**Build: :mag_right:** https://dev.azure.com/dnceng-public/public/_build/results?buildId=1519006
**Error message validated:** `[System.ValueTuple.Tests EXC_BAD_INSTRUCTION`]
**Result validation:** :white_check_mark: Known issue matched with the provided build.
**Validation performed at:** 7/22/2026 12:51:19 PM UTC

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

Start with the linked build and the System.Runtime.Tests.WorkItemExecution failure, focusing on the System.ValueTuple.Tests EXC_BAD_INSTRUCTION result on tvOS. Review pull request #131126 and the associated test output to determine the failure's cause; done means the tvOS test leg completes without this error.

Written by the indexing model from the issue text.