when we made image upload optional we didnt
show the default value properly in the UI. Which
caused confusing. This commit apply the default
values to existing notifiers in the edit pages
and reverts back to using uploadimage=true as the
default value.
This way we are able to edit notification behavior per notifier.
This would be usefull to let some notifiers send notifications,
even when the state doesn't change, or with custom condition.
Signed-off-by: Thibault Chataigner <t.chataigner@criteo.com>