fix(test): speculative attempt to fix trace viewer test flakiness (3) (microsoft#15342)

Author: pavelfeldman

src/index.tsx

@@ -24,7 +24,8 @@ import '@web/common.css';
 (async () => {
   applyTheme();
   if (window.location.protocol !== 'file:') {
-    await new Promise(f => setTimeout(f, 500));
+    if (window.location.href.includes('isUnderTest=true'))
+      await new Promise(f => setTimeout(f, 1000));
     navigator.serviceWorker.register('sw.bundle.js');
     if (!navigator.serviceWorker.controller) {
       await new Promise<void>(f => {