vim-patch:8.2.3908: cannot use a script-local function for 'foldtext'

Problem:    Cannot use a script-local function for 'foldtext'.
Solution:   Expand "s:" and "<SID>". (Yegappan Lakshmanan, closes vim/vim#9411)

27708e6c7b

Cherry-pick test_filter_map.vim change from patch 8.2.3871.

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

test/old/testdir/test_expr.vim

@@ -421,6 +421,7 @@ func Test_printf_misc()
       call assert_equal('[00000あiう]', printf('[%010.7S]', 'あiう'))
 
       call assert_equal('1%', printf('%d%%', 1))
+      call assert_notequal('', printf('%p', "abc"))
   END
   call CheckLegacyAndVim9Success(lines)