Disable Runtime_133209 narrowing cast test on Mono

[Copilot]

Mono is failing Runtime_133209.CheckedNarrowingCast_WithNarrowedOperand with an unexpected OverflowException in CI.

• Disable only the failing theory on Mono using the requested tracking issue:

  [SkipOnMono("https://github.com/dotnet/runtime/issues/100368")]

• Leave the test enabled for CoreCLR and other runtimes.

• Fixes[Mono] CheckedNarrowingCast_WithNarrowedOperand test failing in CI #133293

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[Copilot]

🟢 Approval recommended

The change is a minimal, correctly-scoped Mono-only test suppression that matches existing SkipOnMono usage and does not affect non-Mono test execution.

Pull request overview

Disables the Runtime_133209.CheckedNarrowingCast_WithNarrowedOperand theory when running on Mono by adding a [SkipOnMono] attribute, keeping the test enabled for CoreCLR and other runtimes.

Changes:

• Mark CheckedNarrowingCast_WithNarrowedOperand with [SkipOnMono("https://github.com/dotnet/runtime/issues/100368")] to avoid Mono CI failures.
• Leave all existing test coverage and behavior unchanged for non-Mono runtimes.

File summaries

File	Description
src/tests/JIT/Regression/JitBlue/Runtime_133209/Runtime_133209.cs	Adds a Mono-only skip annotation to the failing theory while preserving execution elsewhere.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Lite

[Copilot]

🟢 Approval recommended

The change is narrowly scoped to disabling only the failing theory on Mono using an established test attribute and a tracking issue link.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0 new
• Review effort level: Lite

[jkotas]

/ba-g failures unrelated to the test being disabled