patch 8.2.2641: display test fails because of lacking redraw

Problem:    Display test fails because of lacking redraw.
Solution:   Add a redraw command.
diff --git a/src/testdir/test_display.vim b/src/testdir/test_display.vim
index 4616da5..754046f 100644
--- a/src/testdir/test_display.vim
+++ b/src/testdir/test_display.vim
@@ -268,12 +268,13 @@
   call assert_fails(':set fillchars=eob:<ff>', 'E474:')
   " default is ~
   new
+  redraw
   call assert_equal('~', Screenline(2))
   set fillchars=eob:+
-  redraw!
+  redraw
   call assert_equal('+', Screenline(2))
   set fillchars=eob:\ 
-  redraw!
+  redraw
   call assert_equal(' ', nr2char(screenchar(2, 1)))
   set fillchars&
   close