feat: remove deprecated `use_if_null_to_convert_nulls_to_bools`

### Description

This rule has been deprecated in Dart 3.11 as described in the changelog:

- https://github.com/dart-lang/sdk/blob/main/CHANGELOG.md#tools
- https://github.com/dart-lang/sdk/commit/01bfcd2a7e4b46695a61aecf5fd861c6ca2eee61


### Additional Context

- https://github.com/dart-lang/sdk/issues/58998#issuecomment-2940669632