RestoreHealth/Fatigue spells have a huge priority even if a success chance is near 0

1. I created an npc with 2 spells; hearth heal and fireball. Has 250 health and 200 magicka.
2. Spawned the npc, and modcurrenthealth -200 and setrestoration 0.
3. Startcombat
4. The npc will keep spamming his healing spell eventhough 95% of the time it fails, wasting precious magicka. He ignores his fireball spell completely.
5. Even with 0 restoration, the npc will mindlessly cast the restoration spell, until his magicka is insufficient. His destruction skill was 50.

If the player would cast absorb skill/damage skill/drain skill on the npc, this would make the npc helpless and look dumb. Tested with healer and assassin class, there is no difference. Tested with 20 restoration and 39 destruction, npc still prefer healing spell.

(RM-4207 from redmine: created on 2017-11-11 by Randy Davin, )