Don't treat Status sub panel as a sub window

It's a system window actually.

Test: manual - repro steps in bug
Test: atest WindowContextTest
Bug: 446773665
Flag: EXEMPT BUGFIX
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:8f34770aecfeed620a44bb67f5bfb1b34423c938
Merged-In: Ia438bf9d3c71c7d56bf10a35a2acb75039514074
Change-Id: Ia438bf9d3c71c7d56bf10a35a2acb75039514074