patch 9.0.1667: regression test doesn't fail when fix is reverted

Problem:    Regression test doesn't fail when fix is reverted.
Solution:   Add "n" to 'cpoptions' instead of using :winsize. (closes #12587,
            issue #12528)
diff --git a/src/testdir/test_scroll_opt.vim b/src/testdir/test_scroll_opt.vim
index 279e547..81670cd 100644
--- a/src/testdir/test_scroll_opt.vim
+++ b/src/testdir/test_scroll_opt.vim
@@ -840,7 +840,7 @@
   let lines =<< trim END
       silent normal yy
       silent normal 19p
-      winsize 0 19
+      set cpoptions+=n
       vsplit
       vertical resize 0
       set foldcolumn=1
@@ -849,9 +849,7 @@
       silent normal 20G
   END
   call writefile(lines, 'XSmoothScrollZeroBot', 'D')
-  let buf = RunVimInTerminal('-u NONE -S XSmoothScrollZeroBot', #{rows: 19, wait_for_ruler: 0})
-  call TermWait(buf, 1000)
-
+  let buf = RunVimInTerminal('-u NONE -S XSmoothScrollZeroBot', #{rows: 19})
   call VerifyScreenDump(buf, 'Test_smoothscroll_zero_bot', {})
 
   call StopVimInTerminal(buf)