[ios] `HybridGlobalization`, functions calculating `matchLength` should return PNSE

Follow up PR for iOS based on changes in https://github.com/dotnet/runtime/pull/105946.

- `IndexOf`/`LastIndexOf` should throw PNSE
- block tests that throw because of that
- re-check that docs about it are up to date