Update node compat warnings test (#8748)

Author: jamesopstad

packages/vite-plugin-cloudflare/playground/node-compat/__tests__/worker-warnings/warnings.spec.ts

@@ -1,12 +1,10 @@
-import { readFileSync, writeFileSync } from "node:fs";
-import { join } from "node:path";
 import dedent from "ts-dedent";
 import { expect, test, vi } from "vitest";
 import { serverLogs } from "../../../__test-utils__";
 
 test("should display warnings if nodejs_compat is missing", async () => {
 	await vi.waitFor(async () => {
-		expect(serverLogs.warns[0]?.replaceAll("\\", "/")).toContain(
+		expect(serverLogs.warns.join("").replaceAll("\\", "/")).toContain(
 			dedent`
 				Unexpected Node.js imports for environment "worker". Do you need to enable the "nodejs_compat" compatibility flag? Refer to https://developers.cloudflare.com/workers/runtime-apis/nodejs/ for more details.
 				 - "node:assert/strict" imported from "worker-warnings/index.ts"