Core/Auras: don't skip stack rule check whenever spells have same ID

- The auras might not have the same amounts due to spellmods

Closes #1626

sql/updates/world/3.3.5/2017_04_15_00_world_335.sql

@@ -0,0 +1,5 @@
+UPDATE `spell_group_stack_rules` SET `stack_rule`=3 WHERE `group_id`=1025;
+DELETE FROM `spell_group_stack_rules` WHERE `group_id` IN (1023,1024);
+INSERT INTO `spell_group_stack_rules` (`group_id`, `stack_rule`) VALUES
+(1023, 4),
+(1024, 4);