After an extremely long intermission (a full year, which a lot of us spent humming “Defying Gravity”), we’re back in the Land of Oz with “Wicked: For Good,” the second half of Jon M. Chu’s screen version of the smash Broadway musical. The first film, 2024’s “Wicked,” was an absolute thrill ride; the second ... well, let’s just say I’m not overwhelmed. But maybe not underwhelmed, either; just whelmed, I guess.