Add Task Root package info to UsageEvent

Bug: 113094946
Test: manual (use "adb shell dumpsys usagestats apptimelimit" to verify
apps at the root of tasks are considered active)
Test: atest cts/tests/tests/app.usage/src/android/app/usage/cts/UsageStatsTest.java#testTaskRootEventField
Test: atest cts/tests/tests/app.usage/src/android/app/usage/cts/UsageStatsTest.java#testUsageSourceAttribution
Test: atest UsageStatsDatabaseTest

Change-Id: I40f86743d33c13892de0e59ae02c9ebddb606ee7
diff --git a/core/tests/coretests/src/android/provider/SettingsBackupTest.java b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
index 87ad3d1..3523c54 100644
--- a/core/tests/coretests/src/android/provider/SettingsBackupTest.java
+++ b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
@@ -120,6 +120,7 @@
                     Settings.Global.APP_IDLE_CONSTANTS,
                     Settings.Global.APP_OPS_CONSTANTS,
                     Settings.Global.APP_STANDBY_ENABLED,
+                    Settings.Global.APP_TIME_LIMIT_USAGE_SOURCE,
                     Settings.Global.ASSISTED_GPS_ENABLED,
                     Settings.Global.AUDIO_SAFE_VOLUME_STATE,
                     Settings.Global.AUTOFILL_COMPAT_MODE_ALLOWED_PACKAGES,