vim-patch:8.2.2399: fold test fails in wide terminal

Problem:    Fold test fails in wide terminal.
Solution:   Adjust the test. (Dominique Pelle, closes vim/vim#7731, closes vim/vim#7739)
https://github.com/vim/vim/commit/7cf0c114d690c91ac88c92a1a6f1b1935cb6410f

src/nvim/testdir/test_fold.vim

@@ -827,7 +827,7 @@ func Test_fold_relative_move()
   set fdm=indent sw=2 wrap tw=80
 
   let content = [ '  foo', '  bar', '  baz',
-              \   repeat('x', 100),
+              \   repeat('x', &columns + 1),
               \   '  foo', '  bar', '  baz'
               \ ]
   call append(0, content)