remove some unused code (#4650)

Author: Rich-Harris

packages/kit/src/core/build/build_server.js

@@ -22,7 +22,6 @@ import root from '__GENERATED__/root.svelte';
 import { respond } from '${runtime}/server/index.js';
 import { set_paths, assets, base } from '${runtime}/paths.js';
 import { set_prerendering } from '${runtime}/env.js';
-import * as user_hooks from ${s(hooks)};
 
 const template = ({ head, body, assets, nonce }) => ${s(template)
 	.replace('%svelte.head%', '" + head + "')