Fix characteristic rro for overridden packages

Overridden packages can have different package names. This change reads
output APKs to parse package name, instead of manifest xml.

Bug: 325011777
Test: boot and idmap2 dump
Change-Id: Iafd792b6fb9c8548441c8ca5c9216be160028088
diff --git a/tools/characteristics_rro_generator.py b/tools/characteristics_rro_generator.py
index 6489673..cf873ee 100644
--- a/tools/characteristics_rro_generator.py
+++ b/tools/characteristics_rro_generator.py
@@ -1,22 +1,14 @@
 #!/usr/bin/env python3
 import sys
-from xml.dom.minidom import parseString
-
-def parse_package(manifest):
-    with open(manifest, 'r') as f:
-        data = f.read()
-    dom = parseString(data)
-    return dom.documentElement.getAttribute('package')
 
 if __name__ == '__main__':
     if len(sys.argv) != 3:
-        sys.exit(f"usage: {sys_argv[0]} target_package_manifest output\n")
-    package_name = parse_package(sys.argv[1])
+        sys.exit(f"usage: {sys_argv[0]} target_package_name output\n")
     with open(sys.argv[2], "w") as f:
         f.write(f'''<?xml version="1.0" encoding="utf-8"?>
-<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="{package_name}.auto_generated_characteristics_rro">
+                <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="{sys.argv[1]}.auto_generated_characteristics_rro">
     <application android:hasCode="false" />
-    <overlay android:targetPackage="{package_name}"
+    <overlay android:targetPackage="{sys.argv[1]}"
              android:isStatic="true"
              android:priority="0" />
 </manifest>