t7422: replace confusing printf with echo

While looping over a counter "i", we do: printf "[submodule \"sm-$i\"]\npath = recursive-submodule-path-$i\n" "$i" So we are passing "$i" as an argument to be filled in, but there is no "%" placeholder in the format string, which is a bit confusing to read. We could switch both instances of "$i" to "%d" (and pass $i twice). But that makes the line even longer. Let's just keep interpolating the value in the string, and drop the confusing extra "$i" argument. And since we are not using any printf specifiers at all, it becomes clear that we can swap it out for echo. We do use a "\n" in the middle of the string, but breaking this into two separate echo statements actually makes it easier to read. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>