patch 8.0.1200: tests switch the bell off twice

Problem:    Tests switch the bell off twice.
Solution:   Don't set 'belloff' in individual tests. (Christian Brabandt)
diff --git a/src/testdir/test_visual.vim b/src/testdir/test_visual.vim
index e4bd100..0e6231f 100644
--- a/src/testdir/test_visual.vim
+++ b/src/testdir/test_visual.vim
@@ -3,7 +3,6 @@
   finish
 endif
 
-set belloff=all
 
 func Test_block_shift_multibyte()
   " Uses double-wide character.
@@ -76,7 +75,6 @@
 endfunc
 
 func Test_visual_mode_reset()
-  set belloff=all
   enew
   let g:msg="Everything's fine."
   enew
@@ -89,5 +87,5 @@
   exe "normal! GV:call TriggerTheProblem()\<CR>"
   call assert_equal("Everything's fine.", g:msg)
 
-  set belloff&
 endfunc
+