[BatteryStatsService] Disable deprecated BatteryUsageStatsAtom

- added dedicated flag to depricate composite atoms

Bug: 353538348
Test: atest PowerStatsTestsRavenwood
Test: atest PowerStatsTests
Flag: com.android.server.power.optimization.disable_composite_battery_usage_stats_atoms
Change-Id: Ia189e61246f4a6595087302f133ca62581b515da
diff --git a/AconfigFlags.bp b/AconfigFlags.bp
index a16aa2d..0e6a94c 100644
--- a/AconfigFlags.bp
+++ b/AconfigFlags.bp
@@ -1490,6 +1490,13 @@
     defaults: ["framework-minus-apex-aconfig-java-defaults"],
 }
 
+java_aconfig_library {
+    name: "backstage_power_flags_lib-host",
+    aconfig_declarations: "backstage_power_flags",
+    host_supported: true,
+    defaults: ["framework-minus-apex-aconfig-java-defaults"],
+}
+
 // Dropbox data
 aconfig_declarations {
     name: "dropbox_flags",