SF: fix refresh rate scoring when frameRateMultipleThreshold is used

We can't exclude layers that are below the frameRateMultipleThreshold
when scoring the higher refresh rates (the ones above the threshold)
as it creates gives the lower refresh rates a higher score (as there are
more layers that are allowed to score them). Instead we use a different
approach which first scores the refresh rates based on all the layers
but the fixed source ones, and then we add the fixed source ones for the
refresh rates below the thresholds and for the above ones only when other
layers already scored them.

Bug: 242283390
Test: newly added unit tests scenarios
Change-Id: Ibe30ddd306265507ceedff6a6a725dadadc50af2