Merge pull request #21438 from ian-liu/settings/wifi/bug1033183_server_certificate_items_are_duplicated_when_disabling_and_reenabling_wifi

Bug 1033183 - [Wifi] Server certificate items are duplicated when disabling and re-enabling wifi, r=arthur
(cherry picked from commit e970c7e69c213fd896383b0dc7b85a1b7b1d7dc8)