Disable non-iOS jobs for WIP iteration

Speeds up CI feedback while the iOS Inner Loop plumbing is unstable —
matches the pattern Matous used in ba239db6 on the
matouskozak/ios-sdk-jobs-macos-26 branch.

- Top-level runPublicJobs → if false (entire public block off)
- Top-level runScheduledPrivateJobs → if false
- In runPrivateJobs: wrap each non-iOS job (Scenario, Affinitized,
  3x Maui Android Release, 2x Maui Android Debug, NativeAOT) in
  ${{ if false }}: with re-indented body.

Active in private: 3 Maui iOS Release + 2 Maui iOS Debug +
4 Maui iOS Inner Loop (Mono/CoreCLR × Simulator/Device) = 9 jobs.

Revert before merge.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: davidnguyen-tech