Fix the optimizations extension to gracefully handle multiple app sta…

…rtups.

Test: Used the trace that was linked in b/380581475
Change-Id: Icec132694b22126470f1b9f26400dd4cc41babda
Fixes: 380581475

ui/src/plugins/dev.perfetto.AndroidStartup/optimizations.ts

@@ -107,7 +107,7 @@ export async function optimizationsTrack(
         '${buildDetails(startup)}' AS details
       `;
     })
-    .join('UNION ALL');
+    .join('UNION ALL '); // The trailing space is important.
 
   const uri = '/android_startups_optimization_status';
   const title = 'Optimization Status';