lsp: Remove reinstall, update config (#18318)

Release Notes:

- Fixed overriding the path of a language server binary for all language
servers. `{"lsp":{"<lsp-name>":{"binary":{"path": "_"}}}}` will now work
for all language servers including those defined by extensions.
- (breaking change) To disable finding lsp adapters in your path, you
must now specify
`{"lsp":{"<lsp-name>":{"binary":{"ignore_system_version": true}}}}`.
Previously this was `{"lsp":{"<lsp-name>":{"binary":{"path_lookup":
false}}}}`. Note that this setting still does not apply to extensions.
- Removed automatic reinstallation of language servers. (It mostly
didn't work)

---------

Co-authored-by: Mikayla <mikayla@zed.dev>

docs/src/languages/rust.md

@@ -64,14 +64,14 @@ You can configure which `rust-analyzer` binary Zed should use.
 
 By default, Zed will try to find a `rust-analyzer` in your `$PATH` and try to use that. If that binary successfully executes `rust-analyzer --help`, it's used. Otherwise, Zed will fall back to installing its own `rust-analyzer` version and using that.
 
-If you want to disable Zed looking for a `rust-analyzer` binary, you can set `path_lookup` to `false` in your `settings.json`:
+If you want to disable Zed looking for a `rust-analyzer` binary, you can set `ignore_system_version` to `true` in your `settings.json`:
 
 ```json
 {
   "lsp": {
     "rust-analyzer": {
       "binary": {
-        "path_lookup": false
+        "ignore_system_version": true
       }
     }
   }