Don't play sound for plain notification
We typically don't play a sound by default for most notifications
However the 'notification' event for the Plasma default notifyrc has a sound by default
Since this event is used by xdg-desktop-portal-kde currently all notifications from Flatpak apps have a sound by default, making them inconsistent with their non-Flatpak counterparts
Remove the default sound to align them
BUG: 457672 FIXED-IN: 5.105
Edited by Nate Graham