patch 9.1.0228: Two unrelated things are tested by a single test

Problem:  Two unrelated things are tested by a single test.
Solution: Split it into two, restoring the old Test_brace_single_line().
          Add missing cleanup to some tests.
          (zeertzjq)

closes: #14323

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_scroll_opt.vim b/src/testdir/test_scroll_opt.vim
index 788870f..d7a7907 100644
--- a/src/testdir/test_scroll_opt.vim
+++ b/src/testdir/test_scroll_opt.vim
@@ -738,6 +738,7 @@
   let &mouse = save_mouse
   let &term = save_term
   let &ttymouse = save_ttymouse
+  bwipe!
 endfunc
 
 " this was dividing by zero
@@ -999,9 +1000,8 @@
 endfunc
 
 func Test_smoothscroll_page()
-  set smoothscroll
-
-  10split | 40vsplit
+  call NewWindow(10, 40)
+  setlocal smoothscroll
   call setline(1, 'abcde '->repeat(150))
 
   exe "norm! \<C-F>"
@@ -1038,7 +1038,7 @@
   exe "norm! \<C-U>"
   call assert_equal(0, winsaveview().skipcol)
 
-  set smoothscroll&
+  bwipe!
 endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab