Bug 1724404 - Inrease the wait time in a test to see if it stops failing. rs=me

--HG--
extra : rebase_source : ecb065fe3d1e9b549961e4142db296a03a8245b0

mail/components/preferences/test/browser/browser_cloudfile.js

@@ -714,7 +714,7 @@ add_task(async function accountListOverflow() {
     );
     await readyPromise;
     // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
-    await new Promise(r => setTimeout(r, 100));
+    await new Promise(r => setTimeout(r, 500));
     if (buttonList.hidden) {
       break;
     }