spec: miqSelectPickerEvent - test it can handle null callback
spec: miqSelectPickerEvent - test it can handle null callback

mainly to address some breakage introduced in #7661
(transferred from ManageIQ/manageiq@085e532a5a69d6528ede6eb749a67f8b3bc8ec94)

ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic