READY - Fix players constantly JUSTHITFLOOR when walking slowly at the top of slopes

Addresses Issue #1151 - but I want some eyeballs on this before we merge it. I tested the GFZ2 ramp, the ramp at the end of GFZ1, other ramps, compared them to 2.2.13's behavior, and everything appears to be identical. I even tested some extreme cases of ramp-sticking, like Network Terminal Zone from 2023 OLDC R1, and everything worked as expected.

I can't help but wonder if this is a piece of leftover code from an earlier iteration of slopes, or if this handles some type of case I'm not aware about.