Move DozeParameters content provider registrations to bg

This uses new async API to register content providers.

Bug: 351766769
Flag: com.android.systemui.register_content_observers_async
Test: unit tests, perfetto trace
Change-Id: Ie7445d396588d302805e8e6b8b713176cb4e404e
diff --git a/packages/SystemUI/aconfig/systemui.aconfig b/packages/SystemUI/aconfig/systemui.aconfig
index 6e6e4b2..b580eb1 100644
--- a/packages/SystemUI/aconfig/systemui.aconfig
+++ b/packages/SystemUI/aconfig/systemui.aconfig
@@ -1171,3 +1171,12 @@
   bug: "345227709"
 }
 
+flag {
+  namespace: "systemui"
+  name: "register_content_observers_async"
+  description: "Use new Async API to register content observers"
+  bug: "316922634"
+  metadata {
+    purpose: PURPOSE_BUGFIX
+  }
+}