Revert "Disable PN spin evolution" for NRSur7dq4Remnant

Description

Turn PN spin evolution back on for NRSur7dq4Remnant fits. It was temporarily disabled to investigate potential nonsmooth behavior but this is now resolved.

API Changes and Justification

Backwards Compatible Changes

• This change introduces no API changes
• This change adds new API calls

Backwards Incompatible Changes

• This change modifies an existing API
• This change removes an existing API

Review Status

The basic code has already been reviewed, but this change still needs to be signed-off: https://git.ligo.org/waveforms/reviews/RemnantFits/-/wikis/home