t7422: replace confusing printf with echo

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>