runtime(syntax-tests): Clear and redraw the ruler line with the shell info

The current contents of sh_01_99.dump and sh_09_99.dump
begin with ":redraw" in the ruler line whereas both the
comment and the need for the redraw command execution imply
blanks "       ".

related: #15150

Signed-off-by: Aliaksei Budavei <0x000c70@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/syntax/testdir/runtest.vim b/runtime/syntax/testdir/runtest.vim
index 32b1663..f2f86c0 100644
--- a/runtime/syntax/testdir/runtest.vim
+++ b/runtime/syntax/testdir/runtest.vim
@@ -307,7 +307,7 @@
 
       " Clear the shell info if there are not enough lines to cause a scroll
       if filetype == 'sh' && IsWinNumOneAtEOF(in_name_and_out_name)
-	call term_sendkeys(buf, ":redraw\<CR>")
+	call term_sendkeys(buf, ":redraw!\<CR>")
       endif
 
       " Make a Screendump every 18 lines of the file: failed/root_NN.dump