Fix external links not working on Android

[Joehuu]

• Framework side of Fix external links not working on Android osu#22790

[bdach]

Not sure how everybody else is feeling but for this one I tend to think we don't need to do the manifest merging thing we did in the game project and we can probably go with how things are right now. Rationale being that:

• there is much less duplication here,
• SampleGame.Android doesn't really need this change for anything as it's just a spinning box (so we may even want to revert that),
• this is a "framework" project, so adding an overlay does nothing for consumers anyway. And if we had android template projects they couldn't use the overlay anyways (as they have to be self-contained).