When a subwiki is empty, the administration should suggest the good UI to install

Steps to reproduce:

1. create a subwiki
2. skip the DW
3. go the the administration of the subwiki

You will see (cf screenshot):

Your wiki seems empty. You may want to import the default XWiki Enterprise wiki which contains a set of useful pages: user profiles, recent activity, administration pages and many more. This wiki is distributed as a XAR file, you can download it from http://maven.xwiki.org/snapshots/org/xwiki/enterprise/xwiki-enterprise-ui-mainwiki-all/5.4-SNAPSHOT/.

which is wrong because it will install the UI for Main Wiki.