[jss-default-unit] maintain unitless and non-px props instead

Currently we maintain many specific props for default px units. It would be easier to maintain only unitless and non-px values, so that the list is shorter.

Ideally we should generate them from mdn data like we do for the vendor prefixer.

- [ ] some values like transition-delay can't be unitless #863

Start by reading the jss-default-unit implementation and the vendor prefixer’s MDN-data generation approach. Determine how to maintain only unitless and non-px values, while accounting for values such as transition-delay that cannot be unitless; done means the shorter generated list preserves correct default-unit behavior.

Written by the indexing model from the issue text.