Core/Spells: Fixed Hunter's Arcane Shot and Multi-Shot focus generation

Closes #19872

sql/updates/world/master/2017_07_13_00_world.sql

@@ -0,0 +1,5 @@
+-- Arcane shot
+DELETE FROM `spell_script_names` WHERE `ScriptName` IN ('spell_hun_arcane_shot','spell_hun_multi_shot');
+INSERT INTO `spell_script_names` (`spell_id`, `ScriptName`) VALUES
+(185358,'spell_hun_arcane_shot'),
+(2643,'spell_hun_multi_shot');