Because the flashlight is made to be scaled by playfield, there are
constant scale factors applied somewhere in the
`PlayfieldAdjustmentContainer` which needs to be reflected in the
flashlight size to keep the size the same.
The factor is specifically 1.6x, computed in {Osu,Catch}PlayfieldAdjustmentContainer.ScalingContainer`.
More generally, I've deduced these factors by logging the difference
between the `flashlightSize` before and after b78abe2f.
Closes https://github.com/ppy/osu/issues/26551
Fix is a bit nuclear (`OnUpdate` should be considered last resort),
but I don't see many better alternatives here as
`ApplyCustomUpdateState` does not work...