Enforce trailing comma in JS on multiline (#30002)

To keep blame info accurate and to avoid [changes like
this](https://github.com/go-gitea/gitea/pull/29977/files#diff-c3422631a14edbe1e508c4b22f0c718db318be08a6e889427802f9b6165d88d6R359),
it's good to always have a trailing comma, so let's enforce it in JS.

This rule is completely automatically fixable with `make lint-js-fix`
and that's what I did here.

web_src/js/features/install.js

@@ -19,7 +19,7 @@ function initPreInstall() {
   const defaultDbHosts = {
     mysql: '127.0.0.1:3306',
     postgres: '127.0.0.1:5432',
-    mssql: '127.0.0.1:1433'
+    mssql: '127.0.0.1:1433',
   };
 
   const dbHost = document.getElementById('db_host');