[Central Surfaces] Make SystemBarAttributesListener a singleton.

Bug:  277762009
Test: compiles
Test: SystemBarAttributesListener still receives bounds changes
Test: `adb shell dumpsys activity service
com.android.systemui/.SystemUIService SystemBarAttributesListener` ->
shows dump
Test: atest SystemBarAttributesListenerTest

Change-Id: Ieb16dccf3b0a1a11633addf18499a5161cdbca92