Reduce test flake for wifi disconnect

wifi disconnect needs couple of seconds wait time for the right
event to pop

Test: None
Bug: 144852765
Change-Id: I520532d778366e04944e773a13e7fa3635151e14
diff --git a/acts/framework/acts/test_utils/wifi/wifi_test_utils.py b/acts/framework/acts/test_utils/wifi/wifi_test_utils.py
index ba99d7f..c540f04 100755
--- a/acts/framework/acts/test_utils/wifi/wifi_test_utils.py
+++ b/acts/framework/acts/test_utils/wifi/wifi_test_utils.py
@@ -638,6 +638,7 @@
     ad.ed.clear_all_events()
     # Setting wifi state.
     ad.droid.wifiToggleState(new_state)
+    time.sleep(2)
     fail_msg = "Failed to set Wi-Fi state to %s on %s." % (new_state,
                                                            ad.serial)
     try: