Fix local search configuration issue

Local search configuration is currently taken into account only after user saves configuration.

Steps to reproduce:

1. In a workspace, click on Manage > Local configuration.
2. Enable Search configuration.
3. Move Quick search in the Existing searches list (to remove it from available searches).
4. Save.
5. Click on the Search tab and check available searches.
   -> Quick search in not in the list -> OK.
6. Log out.
7. Log back in or log in with another user.
8. Go to the workspace on which you configured local search.
9. Click on the Search tab and check available searches.
   -> Quick search in available although it's been disabled. => KO.