notes: do not use strbuf_split*()

notes: do not use strbuf_split*()

When reading copy instructions from the standard input, the program
reads a line, splits it into tokens at whitespace, and trims each of
the tokens before using.  We no longer need to use strbuf just to be
able to trim, as string_list_split*() family now can trim while
splitting a string.

Retire the use of strbuf_split() from this code path.

Note that this loop is a bit sloppy in that it ensures at least
there are two tokens on each line, but ignores if there are extra
tokens on the line.  Tightening it is outside the scope of this
series.

Signed-off-by: Junio C Hamano <gitster@pobox.com>