For a large number of settings, defaults are declared twice -- once in
`xml/templates/civicrm_navigation.tpl` and once in `settings/*.php`.  In
many cases, these are identical/redundant, but there are a couple where the
defaults diverged.

I believe the `civicrm_navigation.tpl` values have generally taken precedent
on new installations, so this commit revises `settings/*.php` to fix any
discrepancies.