Small fixes to the initial data set release

This releases fixes several issues we found in the Caldera data set after the initial release:

1. Prefab "modelscale" fixes.
2. Updated the rest transforms on skeletons with multiple root joints.
3. Disabled floating clutter rocks.

Initial data set release.

Initial data set release of the OpenUSD Call of Duty®: Warzone™ Caldera data set.