plugins/nightlight: Remove premature optimization in updateTransitionTimings()
There are a couple of reasons why it's worth removing it:
- it's error prone. If one forgets to pass correct "force" flag, night light will break
- it contributes some complexity
- updateTransitionTimings() is not called in any hot path and the code that calculates the position of the Sun is not resource intensive
(cherry picked from commit 07f266e7)