[gameplay-a24] differentiate African and Indian war elephants because of their sizes.
maur, pers, sele champion elephants +10% resource costs, training time, health, and attack damage;
cart, kush, ptol champion elephants −10% resource costs, training time, health, and attack damage.
Patch by: @Nescio
Accepted by: @Feldfeld, @borg-
Differential Revision: https://code.wildfiregames.com/D2861