Scripts/VP: minor cleanups and improved Holwing Gale behaivior

* Howling Gale will no longer get stuck in combat when applying periodic damage effects on them
* When damaging a Howling Gale, the target will now stop casting any knockbacks for 10 seconds before slowly starting to build up again

sql/updates/world/4.3.4/2020_09_28_00_world.sql

@@ -0,0 +1,2 @@
+UPDATE `creature_template` SET `RegenHealth`= 0 WHERE `entry`= 45572;
+UPDATE `creature` SET `curhealth`= 0 WHERE `id`= 45572;