test: fix link imports (#13513)

Fixes issue in test suites that import the Link component from
next/link.

test/fields/components/AfterNavLinks.tsx

@@ -4,7 +4,7 @@ import type { PayloadClientReactComponent, SanitizedConfig } from 'payload'
 
 import { NavGroup, useConfig } from '@payloadcms/ui'
 import LinkImport from 'next/link.js'
-const Link = (LinkImport.default || LinkImport) as unknown as typeof LinkImport.default
+const Link = 'default' in LinkImport ? LinkImport.default : LinkImport
 import React from 'react'
 
 const baseClass = 'after-nav-links'