[applets/notifications] Make timeout indicator visible regardless of scale
Right now we try to make the timeout indicator hug the edges of the circular close button icon. However this only works at 100% scale, because at any other scale (including 200%) the scaling methods used by the icon and the indicator differ because icon scaling uses a different codepath. It also fails if the icon is not exactly the Breeze close icon because it comes from a different icon theme with a different appearance.
As a result, the goal is sometimes un-achievable and results in the indicator being partially or fully hidden behind the icon.
To account for these variabilities, this commit changes the timeout indicator to draw on top of the icon, rather than below it. This solves all of the above problems, and results in no visual changes at 100% scale.
BUG: 435004 FIXED-IN: 5.21.4
How it looks at 200% scale for me now: