12281 zvol_swap_003_pos shouldn't use swapadd in cleanup

*** 25,34 ****
--- 25,35 ----
  # Use is subject to license terms.
  #
  
  #
  # Copyright (c) 2013, 2016 by Delphix. All rights reserved.
+ # Copyright 2020 Joyent, Inc.
  #
  
  . $STF_SUITE/include/libtest.shlib
  . $STF_SUITE/tests/functional/zvol/zvol_common.shlib
  . $STF_SUITE/tests/functional/zvol/zvol_swap/zvol_swap.cfg
*** 52,63 ****
          [[ -f $NEW_VFSTAB_FILE ]] && log_must rm -f $NEW_VFSTAB_FILE
          [[ -f $PREV_VFSTAB_FILE ]] && \
              log_must mv $PREV_VFSTAB_FILE $VFSTAB_FILE
          [[ -f $PREV_VFSTAB_FILE ]] && rm -f $PREV_VFSTAB_FILE
  
-         log_must swapadd $VFSTAB_FILE
- 
          if is_swap_inuse $voldev ; then
                  log_must swap -d $voldev
          fi
  
  }
--- 53,62 ----