Revert^2 "Change SysemUIFactory to SystemUIInitializer."

Restores ag/18917521

Reverted in ag/15142270fe17845890d147aca8720a32b8c73ecf

Test: Ran failed test in http://b/238359875
Bug: 235624311
Change-Id: I08457dac1aa09c44f0c9c02349e8c6773587cd84
diff --git a/packages/SystemUI/proguard.flags b/packages/SystemUI/proguard.flags
index 6ffd661..84ebe77 100644
--- a/packages/SystemUI/proguard.flags
+++ b/packages/SystemUI/proguard.flags
@@ -8,9 +8,9 @@
 -keep class com.android.systemui.statusbar.car.CarStatusBar
 -keep class com.android.systemui.statusbar.phone.CentralSurfaces
 -keep class com.android.systemui.statusbar.tv.TvStatusBar
--keep class com.android.systemui.car.CarSystemUIFactory
--keep class com.android.systemui.SystemUIFactory
--keep class com.android.systemui.tv.TvSystemUIFactory
+-keep class ** extends com.android.systemui.SystemUIInitializer {
+    *;
+}
 -keep class * extends com.android.systemui.CoreStartable
 -keep class * implements com.android.systemui.CoreStartable$Injector