Opt tuner settings activity out of edge-to-edge.

Still fun for some, but not for all: this screen is no
longer accessible by end users but is useful in OS
development.

(This quick fix does, however, fix a similar bug in the Demo
Mode activity.)

Fixes: 371216803
Fixes: 341039611
Flag: EXEMPT bugfix in legacy code
Test: adb root \
    && adb shell pm enable com.android.systemui/.tuner.TunerActivity \
    && adb shell am start -n com.android.systemui/.tuner/TunerActivity
Change-Id: Ibb6984ab4b44e12956c5c60b9903b73d12e1cd26