Neovim: TermOpen not fired when fzf#run is used in ftplugin

- [x] I have read through the manual page (`man fzf`)
- [ ] I have the latest version of fzf -- I am running 0.23.0
- [x] I have searched through the existing issues

## Info

- OS
- [x] Linux
- [ ] Mac OS X
- [ ] Windows
- [ ] Etc.
- Shell
- [x] bash
- [ ] zsh
- [ ] fish

## Problem / Steps to reproduce

1. Add to init.vim:
```vim
augroup TermEvents
autocmd!
autocmd TermOpen * unsilent echomsg "TermOpen for ".bufnr()
autocmd TermEnter * unsilent echomsg "TermEnter for ".bufnr()
augroup END
```
2. In after/ftplugin/python.vim, add:
```vim
call fzf#run({'source':['foo','bar','baz'], 'sink': { x -> "" }})
```
3. Close Neovim, reopen, and then open foo.py. Observe that the "TermEnter" line appears in the `:messages`, but "TermOpen" does not.
4. Now run `:call fzf#run({'source':['foo','bar','baz'], 'sink': { x -> "" }})`. Observe that both the "TermEnter" and "TermOpen" lines appear.

**Expected behavior:** 3 and 4 should be consistent. TermOpen should fire when called in ftplugin.