[CI] iOS 27 monotouch-test stalls in NSUrlSession redirect tests with simulator daemon crash loops

## Failure signature

`monotouch-test` starts executing `MonoTests.System.Net.Http.MessageHandlerTest` on the iOS 27 simulator, reaches the NSUrlSession credential/cross-origin redirect tests, then stops producing test output until xharness' 15-minute timeout. The same runs collect repeated `intelligencetasksd` crash reports and a `SpringBoard` crash report.

Representative last test activity:

```text
MonoTests.System.Net.Http.MessageHandlerTest.NSUrlSessionHandlerCredentialsCrossOriginRedirectTarget
```

or immediately after:

```text
[PASS] NSUrlSessionHandlerOriginCredentialCacheNotSentToCrossOriginRedirectTarget
```

## Confirmed occurrences

| PR / head | Build and job | Timed-out variations |
|---|---|---|
| #26200 / `966f7cc95666adf0926c09964990868e5f161864` | [14718622 - monotouch_ios](https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=14718622&view=logs&jobId=a70ed34c-97c9-5ebb-c5be-8e2604f5ffcc) | `Release (trimmable static registrar, NativeAOT)` and `Release (managed static registrar, all optimizations)` |
| #26208 / `34b9f4d4972752561d6769b7f1ef0fbe276e049c` | [14718968 - monotouch_ios](https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=14718968&view=logs&jobId=a70ed34c-97c9-5ebb-c5be-8e2604f5ffcc) | `Release (NativeAOT, .NET 11 defaults)` |

First observed: 2026-07-21 15:25 UTC. Latest observed: 2026-07-21 17:36 UTC. Recurrence: 3 variations across 2 distinct monitored PRs.

## Diagnosis and impact

This is classified as a genuinely flaky iOS 27 simulator/NSUrlSession failure:

- The affected PRs modify unrelated framework bindings.
- Other monotouch-test variations in the same jobs pass.
- The failure is a silent stall rather than an assertion or product build error.
- Repeated simulator-daemon crashes accompany each timeout.

The failure blocks the complete simulator-test stage. The current workaround is to rerun failed jobs after the build is terminal and retry/merge gates permit it. Test reports and crash artifacts have limited retention.

Start with the monotouch-test entry point and MonoTests.System.Net.Http.MessageHandlerTest, focusing on the NSUrlSession credential and cross-origin redirect tests named in the failure signature. Reproduce on the iOS 27 simulator, then inspect xharness timeout output and the accompanying intelligencetasksd and SpringBoard crash reports. Done means the simulator test stage no longer silently stalls in these tests.

Written by the indexing model from the issue text.