Create /metadata/staged-install dir to store staged install failure reasons

Bug: 146343545
Test: presubmit
Change-Id: I513d403f67643929bb8f90212c1054fb3024f12a
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 38ba137..4b64715 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -514,6 +514,8 @@
 
     mkdir /metadata/apex 0700 root system
     mkdir /metadata/apex/sessions 0700 root system
+
+    mkdir /metadata/staged-install 0770 root system
 on late-fs
     # Ensure that tracefs has the correct permissions.
     # This does not work correctly if it is called in post-fs.