refactor(@angular/ssr): remove duplicate resetAngularServerApp method

The `resetAngularServerApp` method was identical to `destroyAngularServerApp` and was mistakenly retained due to an incorrect merge. This commit removes the redundant method.

packages/angular/ssr/src/app.ts

@@ -89,14 +89,6 @@ export function getOrCreateAngularServerApp(): AngularServerApp {
   return (angularServerApp ??= new AngularServerApp());
 }
 
-/**
- * Resets the instance of `AngularServerApp` to undefined, effectively
- * clearing the reference. Use this to recreate the instance.
- */
-export function resetAngularServerApp(): void {
-  angularServerApp = undefined;
-}
-
 /**
  * Destroys the existing `AngularServerApp` instance, releasing associated resources and resetting the
  * reference to `undefined`.