Because Elixir source code can contain `|`, the removed substitution
sometimes broke `lsp_document_symbols()`.
Example:
```
E5108: Error executing lua ...packer/start/telescope.nvim/lua/telescope/make_entry.lua:392: attempt to concatenate local 'symbol_name' (a nil value)
stack traceback:
...packer/start/telescope.nvim/lua/telescope/make_entry.lua:392: in function 'entry_maker'
...scope.nvim/lua/telescope/finders/async_static_finder.lua:17: in function 'new_table'
...acker/start/telescope.nvim/lua/telescope/builtin/lsp.lua:137: in function 'v'
...acker/start/telescope.nvim/lua/telescope/builtin/lsp.lua:500: in function 'v'
...cker/start/telescope.nvim/lua/telescope/builtin/init.lua:496: in function <...cker/start/telescope.nvim/lua/telescope/builtin/init.lua:467>
...ck/packer/start/telescope.nvim/lua/telescope/command.lua:179: in function 'run_command'
...ck/packer/start/telescope.nvim/lua/telescope/command.lua:241: in function 'load_command'
[string ":lua"]:1: in main chunk
```
Closes#874
aa41912ef8