LibWeb: Switch IDL from UseNewAKString to UseDeprecatedAKString

NewAKString is effectively the default for any new IDL interface, so
let's mark this as the default behavior. It also makes it much easier to
figure out whatever interfaces are still left to port over to new AK
String.

Userland/Libraries/LibWeb/UIEvents/FocusEvent.idl

@@ -1,6 +1,6 @@
 #import <UIEvents/UIEvent.idl>
 
-[Exposed=Window, UseNewAKString]
+[Exposed=Window]
 interface FocusEvent : UIEvent {
 
     constructor(DOMString type, optional FocusEventInit eventInitDict = {});

Userland/Libraries/LibWeb/UIEvents/KeyboardEvent.idl

@@ -1,7 +1,7 @@
 #import <UIEvents/EventModifier.idl>
 
 // https://www.w3.org/TR/uievents/#idl-keyboardevent
-[Exposed=Window, UseNewAKString]
+[Exposed=Window]
 interface KeyboardEvent : UIEvent {
 
     constructor(DOMString type, optional KeyboardEventInit eventInitDict = {});

Userland/Libraries/LibWeb/UIEvents/MouseEvent.idl

@@ -1,5 +1,5 @@
 // https://w3c.github.io/uievents/#mouseevent
-[Exposed=Window, UseNewAKString]
+[Exposed=Window]
 interface MouseEvent : UIEvent {
 
     readonly attribute double offsetX;

Userland/Libraries/LibWeb/UIEvents/UIEvent.idl

@@ -1,7 +1,7 @@
 #import <DOM/Event.idl>
 
 // https://w3c.github.io/uievents/#uievent
-[Exposed=Window, UseNewAKString]
+[Exposed=Window]
 interface UIEvent : Event {
     constructor(DOMString type, optional UIEventInit eventInitDict = {});
     readonly attribute Window? view;

Userland/Libraries/LibWeb/UIEvents/WheelEvent.idl

@@ -1,7 +1,7 @@
 #import <UIEvents/MouseEvent.idl>
 
 // https://www.w3.org/TR/uievents/#idl-wheelevent
-[Exposed=Window, UseNewAKString]
+[Exposed=Window]
 interface WheelEvent : MouseEvent {
     // DeltaModeCode
     const unsigned long DOM_DELTA_PIXEL = 0x00;