[2021.2] Settings have no affect before first recompilation

[neon-age]

Found by @Thane5 in 2021.2b

After Editor launch, most settings changes are getting ignored (but UI events and serialization work properly).
Triggering recompilation via any script reimport fixes it.

The cause
prefs instance gets replaced after static initialization, so all classes are referencing the wrong non changing version

(should be property, => instead of =)