test: fix node.js 25 compatibility

packages/better-auth/vitest.config.ts

@@ -2,7 +2,6 @@ import { defineConfig } from "vitest/config";
 
 export default defineConfig({
 	test: {
-		setupFiles: ["./vitest.setup.ts"],
 		poolOptions: {
 			forks: {
 				execArgv: ["--expose-gc"],

packages/better-auth/vitest.setup.ts

@@ -1,7 +0,0 @@
-if (
-	typeof globalThis.localStorage !== "undefined" &&
-	+process.versions.node.split(".")[0]! >= 25
-) {
-	// @ts-expect-error
-	globalThis.localStorage = undefined;
-}