Core/Events: refactored battleground holiday assignments. Instead of going with shitty bitmasks we now accept plain battleground ids instead

sql/updates/world/custom/custom_2020_01_11_04_world.sql

@@ -0,0 +1,14 @@
+ALTER TABLE `game_event_battleground_holiday`   
+	CHANGE `eventEntry` `EventEntry` TINYINT(3) UNSIGNED NOT NULL COMMENT 'game_event EventEntry identifier',
+	CHANGE `bgflag` `BattlegroundID` INT(3) UNSIGNED DEFAULT 0 NOT NULL;
+
+TRUNCATE TABLE `game_event_battleground_holiday`;
+INSERT INTO `game_event_battleground_holiday` (`EventEntry`, `BattlegroundID`) VALUES
+(18, 1),
+(19, 2),
+(20, 3),
+(21, 7),
+(53, 9),
+(54, 30),
+(82, 120),
+(83, 108);