I'm not sure if it's worth supporting a terminal that mishandles unknown OSC
and CSI sequences. Better to fix the terminal. Note that there are Emacs
terminals available that don't have this problems; for example "vterm".
Because we reload changed function files, a common issue on upgrading
to 3.4.0 is that fish_title causes errors.
So we simply use the oldschool syntax.
I have no idea why this kept one component in the one case and none in
the other.
Because we already aggressively shorten the command, we can keep the directory.
The code to override the `(status current-command) was present`, but not
handled in either the default `fish_title` function or the fallback.
Closes#7444.
The prompt is a fallback that is overridden via a function file
anyway.
Do that with the title as well, so we can use just builtins.
This removes error messages when $fish_function_path is borked.
