lsp: Do not notify all language servers on file save (#17756)

This is not an ideal solution to
https://github.com/fasterthanlime/zed-diags-readme, but current status
quo is not great either; we were just going through all of the language
servers and notifying them, whereas we should ideally do it based on a
glob.
/cc @fasterthanlime

Release Notes:

- N/A