Fix old audio engine mute button showing when useCustomUnlockedButton is set (#17363)

When `useCustomUnlockedButton` is set to `true` on the old audio engine,
it is still getting shown when the audio engine V2 implementation is
initialized and it's state gets immediately set to `suspended`.

This change fixes the issue by checking the mute button's `enabled` flag
before showing it.

Author: docEdub

packages/dev/core/src/AudioV2/webAudio/webAudioUnmuteUI.ts

@@ -68,7 +68,7 @@ export class _WebAudioUnmuteUI {
     }
 
     private _show(): void {
-        if (!this._button) {
+        if (!this._button || !this._enabled) {
             return;
         }