Notify overlays changed when target package upgraded

Per linked bug, when a target package is upgraded, the overlays are not refreshed. This means the PixelThemeOverlay was never added back for the targeted app and wasn't loaded into AssetManager.

This is a regression originally introduced by ag/3986153, reverted, and again introduced in ag/4032433. The code went back and forth several times, but essentially `onOverlaysChanged` must be called somewhere inside `onTargetChanged`, `onTargetUpgrading`, or `onTargetUpgraded`. Through a series of CLs, all those cases ended up being removed.

`onTargetUpgraded` was chosen in this CL because it is called less frequently than `onTargetChanged` and after `onTargetUpgrading`, to prevent extra unncessary calls.

Bug: 122641077

Test: fix with Wellbeing on P
Test: fix with Wellbeing on Q
Test: verified exact upgrade steps on linked bug on P

Change-Id: I1ac4d67c318102d466dfcc1529c8a3f81ec91acb