DB/Spell: stop some auras from removing stealth

- They have damage class melee and proc PROC_FLAG_TAKEN_SPELL_MELEE_DMG_CLASS
- Sated/Exhaustion are negative auras, counts as negative spell flag, and stealth drops too

Closes #18421
Closes #18553

(cherry picked from commit a39ccee)

sql/updates/world/master/2018_04_29_02_world_2016_12_29_00_world_335.sql

@@ -0,0 +1,4 @@
+DELETE FROM `spell_custom_attr` WHERE `entry` IN (57723, 57724);
+INSERT INTO `spell_custom_attr` (`entry`, `attributes`) VALUES
+(57723, 0x40), -- Exhaustion
+(57724, 0x40); -- Sated