The ornamental design for a coffeepadbin, as shown and described.
FIG. 1 is a top front perspective view of a coffee pad bin showing my new design, with the rear, left, and right top perspective views being identical thereto;
FIG. 2 is a top plan view thereof;
FIG. 3 is a front elevational view thereof, with the rear, left, and right side elevational views being identical thereto; and,