Move the tile decoration content description from the icon to the parent box

Resizing handles don't have an icon and the content description was not read as a result in Talkback

Test: manually selecting the tile's handle with Talkback
Flag: com.android.systemui.qs_ui_refactor_compose_fragment
Fixes: 412325583
Change-Id: I757333bec70fc6c84d96ab233a29a15b288f991b