Remove unused translations

They weren't caught by `i18n-tasks` because there are places were we use
`t("budgets.edit.#{variable}"`, which marks as used all translations
starting with `budgets.edit`

config/locales/en/admin.yml

@@ -111,8 +111,6 @@ en:
         empty_trackers: "There are no trackers"
         name: "Name"
         selected: "Selected"
-        cancel: "Cancel"
-        save: "Save"
       destroy:
         success_notice: Budget deleted successfully
         unable_notice: You cannot delete a budget that has associated investments

config/locales/es/admin.yml

@@ -111,8 +111,6 @@ es:
         empty_trackers: "No hay gestores de seguimiento"
         name: "Nombre"
         selected: "Seleccionado"
-        cancel: "Cancelar"
-        save: "Guardar"
       destroy:
         success_notice: Presupuesto eliminado correctamente
         unable_notice: No se puede eliminar un presupuesto con proyectos asociados