In column view, time slots are always visible. selectFirstAvailableTimeSlotNextMonth
could click stale time slots from the current month before the schedule data refreshed
for the new month. Since isQuickAvailabilityCheckFeatureEnabled is always true in E2E,
isTimeSlotAvailable would check the stale slot against the new month's schedule data,
find no match, and permanently disable the confirm button.

Fix: wait for initial schedule data to load before setting up a waitForResponse listener
for getSchedule, then click incrementMonth and await the response before selecting slots.

Ported from calcom/cal#1107.