Run preloads_copy.sh as system:system

Root is not required, and most importantly system_server won't be able delete
preloads folder during cleanup.

Bug: 30280710
Change-Id: I41890834467cc51b7b4ebd9c2918a47904f0b377

Author: Fyodor Kupolov

cppreopts/cppreopts.rc

@@ -16,14 +16,14 @@ on property:sys.cppreopt=requested && property:ro.boot.slot_suffix=_a
     mount ext4 /dev/block/bootdevice/by-name/system_b /postinstall ro nosuid nodev noexec
     exec - root -- /system/bin/cppreopts.sh /postinstall
     # Optional script to copy additional preloaded content to data directory
-    exec - root root system -- /system/bin/preloads_copy.sh /postinstall
+    exec - system system -- /system/bin/preloads_copy.sh /postinstall
     umount /postinstall
     setprop sys.cppreopt finished
 
 on property:sys.cppreopt=requested && property:ro.boot.slot_suffix=_b
     mount ext4 /dev/block/bootdevice/by-name/system_a /postinstall ro nosuid nodev noexec
     exec - root -- /system/bin/cppreopts.sh /postinstall
     # Optional script to copy additional preloaded content to data directory
-    exec - root root system -- /system/bin/preloads_copy.sh /postinstall
+    exec - system system -- /system/bin/preloads_copy.sh /postinstall
     umount /postinstall
     setprop sys.cppreopt finished