[RFR] Fix to switch_to.alert call

[tpapaioa]

In PR #10237 the fix to replace deprecated switch_to_alert() with the property method switch_to.alert incorrectly used switch_to.alert(), which led to errors like the following when a popup / alert is found:

        try:
>           return self.selenium.switch_to.alert()
E           TypeError: 'Alert' object is not callable

cfme/utils/appliance/implementations/common.py:38: TypeError (cfme/fixtures/log.py:84)

This PR makes the fix and includes a PRT test that ran into this problem.

{{ pytest: -v -k test_zone_crud cfme/tests/configure/test_zones.py }}