test(frontend): let Profile L use its declared waitFor budget

The Profile L case waits up to 15s for the mounted-row cap, but the vitest per-test default is 5s, so that budget was unreachable. Under the release qualification VM's load the case timed out at 5s and failed exact preflight for v6.4.5-rc.3 (packet 20260923T082318Z-release), even though the candidate frontend tree is byte-identical to checkpoints that passed. Set the test-level timeout to 20s so the declared 15s waitFor governs.

Change-source: pulse-maintainer

frontend-modern/src/components/Infrastructure/__tests__/UnifiedResourceTable.performance.contract.test.tsx

@@ -1215,7 +1215,7 @@ describe('UnifiedResourceTable performance contract', () => {
         },
         { timeout: 15000 },
       );
-    });
+    }, 20000);
   });
 
   describe('Grouped vs flat mode contract', () => {