test: increase sleep time to allow GC to perform cleanup (#20019)

On CI system the test randomly fails because the GC seems not
to clean up ComponentLocator memory within the 5 milliseconds.
However, running the test in isolation works fine.
This change increases the delay between the GC requests
to try to make the test more reliable.

flow-server/src/test/java/com/vaadin/flow/ComponentTrackerTest.java

@@ -156,10 +156,10 @@ public void memoryIsReleased() throws Exception {
     private boolean isCleared(Map<?, ?> map) throws InterruptedException {
         for (int i = 0; i < 5; i++) {
             System.gc();
-            if (map.size() == 0) {
+            if (map.isEmpty()) {
                 return true;
             }
-            Thread.sleep(1);
+            Thread.sleep(100);
         }
         return false;
     }