[vim] Remove unnecessary term_wait workaround

The issue is fixed in https://github.com/vim/vim/commit/1232624ae5b56c167c5982a2620f736c4bbc19ef

plugin/fzf.vim

@@ -700,8 +700,7 @@ function! s:execute_term(dict, command, temps) abort
       call termopen(command, fzf)
     else
       let t = term_start([&shell, &shellcmdflag, command], {'curwin': fzf.buf, 'exit_cb': function(fzf.on_exit)})
-      " FIXME: https://github.com/vim/vim/issues/1998
-      if !has('nvim') && !s:is_win
+      if !has('patch-8.0.1261') && !has('nvim') && !s:is_win
         call term_wait(t, 20)
       endif
     endif