Revert #2530 "Make VarbitChanged only fire once..."

This broke the speccounter plugin, and is moderately incorrect because client scripts can update varbits before a tick has happened, and the event should reflect that.

runelite-api/src/main/java/net/runelite/api/Client.java

@@ -192,8 +192,6 @@ public interface Client extends GameEngine
 	@VisibleForDevtools
 	void setVarbitValue(int varbit, int value);
 
-	boolean shouldPostVarbitEvent();
-
 	HashTable getWidgetFlags();
 
 	HashTable getComponentTable();