Fix flicking in App Spread when there are many apps open

I'm not sure anymore if I logged this bug and where so I can't link it here. And I'll just describe it a bit here 😄

Basically when you open a lot of apps (10+), the apps on the right end of the App Spread won't be flickable anymore so you can only select them or swipe vertically to close. So when you are way past 10 apps and at the end of the App Spread, you can't flick to go back to the start anymore.

Apparently, the z-index of the app surfaces that are affected by this issue become higher than the Spread component. This can be seen in the test I performed where I put a blue rectangle in the Spread component and set the z-index of the Spread component to the current app count minus 1. So there will always be an app at the end that will be on top as shown in the image below.