This change is a step towards simplifying `TestWithMultipleFormatsHelper` to the point where we'll be
able to handle special cases (e.g. apple's handling of nan) by changing which inputs are fed into the helper, instead of skipping them within the helper and not testing them at all.

Extracting the loop also improves readability by reducing indentation.

PiperOrigin-RevId: 631038465
Change-Id: I8b2458539d9d276093d8e7b5f373efba6a33800c