[Dual Shade] Fix inconsistent clock size values on the lockscreen.

The problem: The lockscreen clock size in KeyguardClockViewModel was
different from the value of the same in LockscreenContentViewModel.

The culprit: KeyguardClockInteractor.clockSize can be overriden by a
user setting which forces the clock size to always be small. This
override is calculated in KeyguardClockViewModel, but
LockscreenContentViewModel was unaware of it and read the non-overriden
value.

The solution: Make KeyguardClockInteractor.clockSize the single source
of truth, after taking into account the override. Both view-models read
from it without applying any further business logic.

Bug: 395060439
Test: Manually tested by observing notification placement on lockscreen
 in both small and large clock configuration.
Test: Added and updated unit tests.
Test: Existing unit tests still pass.
Flag: com.android.systemui.scene_container
Change-Id: I1946e9d6d5659de368b89bbfbb4398598a164f81