cppreopts: using /dev/block/by-name/system_{ab} for postinstall

/dev/block/bootdevice/by-name/system_{ab} should not be used because
there is no requirement of a single boot device. Replace it with
/dev/block/by-name/system_{ab}.

Bug: 78613232
Test: factory wipe, reboot device to check logcat

Change-Id: Ia3a476ef7a4b271eff90f44ef4e04fdbee17052b
1 file changed