Fix RegionSampler crashes

RegionSampler was crashing due to (1) the LS Smartspace not checking for
the View's existence in the RegionSampler map and (2) adding regions
that were out of bounds. These crashes prevented RegionSampler from
working properly (i.e. being able to edit thresholds from ag/21145349).

This change also addresses some faulty logic in ClockEventController that was causing only the large clock view to be sampled. Now, both the small clock and large clock are being sampled when there's a layout change detected.

Bug: 202758428
Flag: region_sampling
Test: manual (verified no more error logs related to RegionSampler in Logcat)
Change-Id: I7895f1c2aa8fb19feac325df71d8b7f04c39717b