XWIKI-7883: document.get(property) displays key not value for a property of type database list which has key and value in multiwiki mode.

* Now, DBLIstClass#getDBList() executes the query on the good database.
* I have replaced xwiki.search() by QueryManager#createQuery() to not increase the technical debt.
* Bug fixed!
XWIKI-7883: document.get(property) displays key not value for a property of type database list which has key and value in multiwiki mode.

* Apply Thomas M suggestion.
Merge pull request #164 from gdelhumeau/XWIKI-7883

XWIKI-7883: document.get(property) displays key not value for a property...