Ensure that we sanitize any `AC::Parameters` in `find_or_initialize_with_errors`.

 As we are already slicing the Hash, we must be sure that this method will send
 a "safe" object down to the other finder methods that will use the Hash entries
 to do the querying.
Merge pull request #3162 from plataformatec/lm-sanitizer-to-hash

Do not pass down 'ActionController::Parameters' to outside the controller