otapreopt: Collect and print size of artifacts

if test -n "$SLOT_SUFFIX" ; then

  if test -d /data/ota/$SLOT_SUFFIX/dalvik-cache ; then

    log -p i -t otapreopt_slot "Moving A/B artifacts for slot ${SLOT_SUFFIX}."

    OLD_SIZE=$(du -h -s /data/dalvik-cache)

    rm -rf /data/dalvik-cache/*

    NEW_SIZE=$(du -h -s /data/ota/$SLOT_SUFFIX/dalvik-cache)

    mv /data/ota/$SLOT_SUFFIX/dalvik-cache/* /data/dalvik-cache/

    rmdir /data/ota/$SLOT_SUFFIX/dalvik-cache

    rmdir /data/ota/$SLOT_SUFFIX

    log -p i -t otapreopt_slot "Moved ${NEW_SIZE} over ${OLD_SIZE}"

  else

    log -p i -t otapreopt_slot "No A/B artifacts found for slot ${SLOT_SUFFIX}."

  fi