The enemy AI player D.Va (Veteran difficulty) did not use Self-Destruct at all over the duration of the 17+ minute game.
Map: Battlefield of Eternity
AI Difficulty: Veteran + AI Teammates
When de-meched, she would use Big Shot as normal but would stay in Pilot mode unless her Health dropped to the point where she was about to die, even though her Call Mech bar was filled. (may be intentional behavior)