Follow-up on #18447: Unintentional deletion during merge-conflicts resolution (#20991)

After #18447 was merged, I reviewed the PR code as usual. During this
review, I realized that some code was unintentionally removed when I was
resolving merge conflicts in #18447.

Sorry!

Release Notes:

- N/A

crates/languages/src/go.rs

@@ -139,7 +139,8 @@ impl super::LspAdapter for GoLspAdapter {
         let gobin_dir = container_dir.join("gobin");
         fs::create_dir_all(&gobin_dir).await?;
 
-        let install_output = util::command::new_smol_command("go")
+        let go = delegate.which("go".as_ref()).await.unwrap_or("go".into());
+        let install_output = util::command::new_smol_command(go)
             .env("GO111MODULE", "on")
             .env("GOBIN", &gobin_dir)
             .args(["install", "golang.org/x/tools/gopls@latest"])