Make custom dlg for SmoothNeghbours disable properties specified from script.

Small cosmetic fix touching dialog run from scripts as well, so done in this ticket.

Refs #7744
(cherry picked from commit 2069396be4bdb1e4630e92a014fcaee6b885bbfb)
Make dialogs launched from script interpreter use default values.

Refs #7744
(cherry picked from commit f0875eb7add11630fb675eddc09852c16cedc0e5)