Set the default value of 'FirstLevelNavigationItems' configuration to a lower value to avoid too much databases from loading in the initial page

Signed-off-by: Madhura Jayaratne <madhura.cj@gmail.com>
Merge branch 'master' of github.com:phpmyadmin/phpmyadmin
Merge branch 'master' of github.com:phpmyadmin/phpmyadmin