[CI] Flaky: monotouch-test macOS NativeAOT configurations TimedOut

## Flaky Test Report (automated)

**Test:** monotouch-test (macOS, NativeAOT configurations)
**Platform:** macOS
**Category:** Flaky
**Period:** June 8–15, 2026

### Occurrence Summary

| PR | Build | Configuration | Bot | Direct Link |
|----|-------|---------------|-----|-------------|
| #25657 | 14376282 | NativeAOT | VSCXSDKs-MINI-043.Tahoe.arm64 | [monotouch_macos → Run tests](https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=14376282&view=logs) |
| #25586 | 14376290 | trimmable static registrar, NativeAOT | VSM-XAM-08.Tahoe.arm64 | [monotouch_macos → Run tests](https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=14376290&view=logs) |

**Total:** Failed in 2 builds across 2 unrelated PRs this week.

### Error Details

The monotouch-test suite on macOS completes all NativeAOT configurations successfully except one which times out (`TimedOut` status in xharness). The specific configuration that times out varies between runs:

**Build 14376282 (PR #25657):**
```
NativeAOT → TimedOut
```

**Build 14376290 (PR #25586):**
```
trimmable static registrar, NativeAOT → TimedOut
```

All other NativeAOT configurations in both builds pass (including NativeAOT ARM64, NativeAOT x64, .NET 11 defaults, trimmable static registrar NativeAOT ARM64/x64). This suggests a timing/resource issue rather than a consistent test failure.

### Classification

This failure was identified as **flaky** because:
- It appeared across 2 unrelated PRs
- Different NativeAOT configurations time out each time (not always the same config)
- All other NativeAOT configs pass in the same run
- The behavior is consistent with resource exhaustion or slow NativeAOT compilation on macOS hitting a timeout threshold

### Possible Root Cause

NativeAOT compilation on macOS for the full monotouch-test suite is resource-intensive. Some configurations may occasionally exceed the test timeout when running on heavily loaded bots or when NativeAOT compilation is slightly slower.

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*This issue was automatically generated by CI post-mortem analysis.*