Revert "fix: msw 関連のモジュールが yarn dev 時解決に失敗する"

This reverts commit 68e03ee.

mswjs/msw#1267 (comment) 解決済みのため

frontend/mocks/server.ts

@@ -1,3 +1,4 @@
+import { setupServer } from "msw/node";
 import { handlers } from "./handlers";
 
-export const server = require("msw/node").setupServer(...handlers);
+export const server = setupServer(...handlers);