Can I plug corded light fixtures in outlets in ceiling per code?
Corded lights are legal to be plugged into outlets. Although your LED lights are wired for a 15 amp circuit the lamp draws much less, the directions state 8 fixtures for a 15 amp circuit, I would guess the 8 lamps draw a total of 1200w or less,  but in any case the NEC allows manufacturer instructions to override code in some cases as long as the product is listed. NEC 400.8 provides the locations that can't be used but if the outlet is visible (not concealed) it is legal .