test: avoid repeated screen lines in expected states

This is the command invoked repeatedly to make the changes:

    :%s/^\(.*\)|\%(\*\(\d\+\)\)\?$\n\1|\%(\*\(\d\+\)\)\?$/\=submatch(1)..'|*'..(max([str2nr(submatch(2)),1])+max([str2nr(submatch(3)),1]))/g

test/functional/vimscript/match_functions_spec.lua

@@ -148,9 +148,7 @@ describe('matchaddpos()', function()
     }}, funcs.getmatches())
     screen:expect([[
       ^a{1:b}cdef                                  |
-      {2:~                                       }|
-      {2:~                                       }|
-      {2:~                                       }|
+      {2:~                                       }|*3
                                               |
     ]], {[1] = {foreground = Screen.colors.Red}, [2] = {bold = true, foreground = Screen.colors.Blue1}})
   end)