[Operational Issue]: OSX_arm64 scenario tests repeatedly time out after 30 minutes

### Error

The `OSX_arm64` official-build leg times out during scenario tests after 30 minutes:

```text
##[error]The task has timed out.
```

The timeout occurs while running `src/scenario-tests/eng/common/build.sh --test`. This occurred in 4 `main` shipping builds during the last 8 days.

### Links

- Latest: https://dev.azure.com/dnceng/internal/_build/results?buildId=3035767
- https://dev.azure.com/dnceng/internal/_build/results?buildId=3032897
- https://dev.azure.com/dnceng/internal/_build/results?buildId=3031984
- https://dev.azure.com/dnceng/internal/_build/results?buildId=3030052

### Root Cause

Unknown. The test task reaches its 30-minute timeout without reporting a test failure.

### Blocking

- [ ] This issue is blocking

### Affected Releases

- [ ] .NET 10
- [ ] .NET 10 (SDK band build)
- [x] .NET 11

Start with src/scenario-tests/eng/common/build.sh --test and compare the four linked OSX_arm64 shipping-build results, focusing on where execution reaches the 30-minute timeout without a reported test failure. Done means identifying the cause and ensuring the OSX_arm64 scenario-test leg completes without timing out.

Written by the indexing model from the issue text.