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.

playwright.config.js

@@ -20,7 +20,7 @@ export default {
      * Maximum time expect() should wait for the condition to be met.
      * For example in `await expect(locator).toHaveText();`
      */
-    timeout: 2000
+    timeout: 2000,
   },
 
   /* Fail the build on CI if you accidentally left test.only in the source code. */