Notif redesign: Improve the way we display the work badge

Now instead of fetching the app icon including the work badge and
passing that to launcher to normalize, we do something more similar to
what launcher does by fetching the app icon without the badge and adding
the badge afterwards.

Bug: 371174789
Test: manually verified that notifications look good from both main
profile and work profile apps; also checked the dumps to verify that
things are cached correctly and the cache is cleared when there are no
notifications from an app in either profile
Flag: android.app.notifications_redesign_app_icons

Change-Id: I451998619dc2d7fcff8a88c85a1bfb46085c504c