bug#61748: 27.2; Eglot should use shell-file-name when launching the language server for a remote file

[jeberger]

Huh, I just noticed that Emacs doesn't use my configured value for 
`tramp-remote-path`. I've set it through `customize` and it has the
correct value in `custom.el` but `C-h v` shows that it has been
reset to another value that doesn't include `tramp-own-remote-path`.

It was fine when I first set it up (in 2016 according to the `hg`
log) but it no longer is :(

The issue is not in my config, I can reproduce it with:

```
emacs -Q --eval "(custom-set-variables '(tramp-remote-path 
(tramp-own-remote-path tramp-default-remote-path)))" -l tramp
```

Then `C-h v` or `(customize-variable 'tramp-remote-path)` shows
that it has been reset to:

```
(tramp-default-remote-path "/bin" "/usr/bin" "/sbin" "/usr/sbin" 
"/usr/local/bin" "/usr/local/sbin" "/local/bin" "/local/freeware/bin" 
"/local/gnu/bin" "/usr/freeware/bin" "/usr/pkg/bin" "/usr/contrib/bin" 
"/opt/bin" "/opt/sbin" "/opt/local/bin")
```

Other Tramp customizations (e.g. `'(tramp-verbose 10)`) work fine.

Regards,
Jérôme