combined_deforestion image values changed (stable nonforest) and new …

[tawoodard]

Changed/fixed 2 things:

1. The combined deforestation image, or review image, was giving stable nonforest the value of 0 (the same as background). It should be giving it a value of 4.
2. new wording on legend categories (per Rishi's specifications on 11/4/24 in TerrSet's UDef-A). Changing this to match.

Old:
1 = "Forest at the start of HRP"
2 = "Deforestation within CAL"
3 = "Deforestation within CNF"

New:
1 = 'Stable Forest (HRP)'
2 = 'Forest Loss within CAL'
3 = 'Forest Loss within CNF'
4 = 'Stable Nonforest (HRP)'