smbtorture: fix smb2.notify.mask test

smbtorture: fix smb2.notify.mask test

The strange function custom_smb2_create() was somehow causing
NT_STATUS_DELETE_PENDING failures:

  failure: mask [
  (../../source4/torture/smb2/notify.c:490) Incorrect status NT_STATUS_DELETE_PENDING - should be NT_STATUS_OK
  ]

I couldn't figure out what was causing this exactly, but after doing these
cleanups the error went away.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15732

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>