The ornamental design for a foldabletrestle, as shown and described.
FIG. 1 is a perspective view of the foldable trestle showing top, front and
left end, the right end is a mirror image of the left end of the foldable
trestle;
FIG. 2 is a perspective view showing the bottom, rear and left end; and
FIG. 3 is a perspective view of the foldable trestle of FIGS. 1 and 2 in
folded condition showing the top, rear and left end.