isOutputRedundant badly failed when two screens had
the exact same geometry (that should be, the base
case for "cloning" screens.
now the logic is:
a screen is redundant if:
- its geometry is contained in another one
- if their resolutions are different, the "biggest" one wins
- if they have the same geometry, the one with the lowest id wins (arbitrary, but gives reproducible behavior and makes the primary
BUG:375507