fix(i18n): apply unused translations (#40599)

* fix: Apply unused translations

Applies the following unused translation keys
(discovered with script from #40585):
- HeatMap uses plural form of points unless points=1
- Camper uses plural form of points unless points=1
- DeleteModal uses delete title instead of button text
- UpdateEmail page uses verify email translation correctly

Still unused:
- buttons.reset-lesson (replaced by reset-code?)
- settings.username validation error messages (loaded dynamically)
- flash messages (sent from server?)
- donate.additional (removed from page, discussed to keep this key)

Signed-off-by: nhcarrigan <nhcarrigan@gmail.com>

* revert: Undo manual plurality

Signed-off-by: nhcarrigan <nhcarrigan@gmail.com>

* fix: use buttons.reset-lesson key

Co-authored-by: moT01 <20648924+moT01@users.noreply.github.com>

client/src/pages/update-email.js

@@ -120,7 +120,7 @@ class UpdateEmail extends Component {
                   >
                     {isNewEmail
                       ? t('buttons.update-email')
-                      : t('misc.verify-email')}
+                      : t('buttons.verify-email')}
                   </Button>
                 </Form>
                 <p className='text-center'>