applets/notifications: use `Plasmoid.self` in `Globals.adopt`
Plasmoid will remain an object in QML after the system tray is deleted,
but we need !Plasmoid
to return true in order to delete the plasmoid
item in Globals.plasmoids
, so use Plasmoid.self
instead.
BUG: 459249 FIXED-IN: 5.26
Edited by Fushan Wen