Track debug key changes in libcore/

Add ".source" to the debug key for the time zone update
via APK data:

i.e.
core_library.timezone>.source<.data_status

Bug: 118242715
Test: adb shell dumpsys runtime
Change-Id: I0f19faeef08ed19fe5482727280a17b49d8f923b
diff --git a/services/core/java/com/android/server/RuntimeService.java b/services/core/java/com/android/server/RuntimeService.java
index ccfac80..bb39ccc 100644
--- a/services/core/java/com/android/server/RuntimeService.java
+++ b/services/core/java/com/android/server/RuntimeService.java
@@ -94,7 +94,7 @@
         // Add /data tz data set using the DistroVersion class (which libcore cannot use).
         // This update mechanism will be removed after the time zone APEX is launched so this
         // untidiness will disappear with it.
-        String debugKeyPrefix = "core_library.timezone.data_";
+        String debugKeyPrefix = "core_library.timezone.source.data_";
         String versionFileName = TimeZoneDataFiles.getDataTimeZoneFile(
                 TimeZoneDistro.DISTRO_VERSION_FILE_NAME);
         addDistroVersionDebugInfo(versionFileName, debugKeyPrefix, coreLibraryDebugInfo);