mfc-candidates: move pretty printing into lua

d51c59002367 moved the MFC hash matching logic into a lua utility
script but left the output formatting in the shell script. Simplify this
slightly by just printing the formatted output from lua.

Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D44836

(cherry picked from commit 793745fad866f65863ab3b16a17bdf18dc779efd)