Core/Scripts: fix Nightfall proc chance and reduce it for victims with level above 60

Closes #15734

missing code
(cherry picked from commit eac9c1f0b992fd3622fd7dd864b2acc2781ec778)

sql/updates/world/4.3.4/2022_01_29_02_world_2017_02_21_01_world.sql

@@ -0,0 +1,2 @@
+-- UPDATE `item_template` SET `spellppmRate_1`=2.5, `ScriptName`='item_generic_limit_chance_above_60' WHERE `entry`=19169;
+UPDATE `item_template_addon` SET `SpellPPMChance`=2.5 WHERE `Id`=19169;