chore: minor change to avoid tests flakiness

Author: juanmigdr

app/core/Engine/Engine.ts

@@ -274,6 +274,12 @@ export class Engine {
     CaveatSpecificationConstraint
   >;
 
+  /**
+   * Shared token list service. Stored so destroyEngineInstance can call
+   * destroy() to abort in-flight requests and clear the TanStack Query cache.
+   */
+  private tokenListService: TokenListService;
+
   /**
    * Creates a CoreController instance
    */
@@ -289,6 +295,7 @@ export class Engine {
 
     const codefiTokenApiV2 = new CodefiTokenPricesServiceV2();
     const tokenListService = new TokenListService();
+    this.tokenListService = tokenListService;
 
     const initRequest = {
       getState: () => store.getState(),
@@ -1219,6 +1226,7 @@ export class Engine {
         controller.destroy();
       }
     });
+    this.tokenListService.destroy();
     this.removeAllListeners();
     await this.resetState();