There is no shorter way. You can change the LEFT with length calculation to improve:
=LEFT(B2,len(B2)-4)&"/"&MID(B2,2,2)&"/"&MID(B2,4,2)&" "&LEFT(A2,len(A2)-2)&":"&MID(A2,2,2)
The above is not true date-time calculation, just string manipulation.