merge tests: expect slight differences in output for recursive vs. ort

merge tests: expect slight differences in output for recursive vs. ort

The ort merge strategy has some slight differences in commit
descriptions (shortened hashes), stdout vs stderr, and in conflict
messages.  Also, builtin/merge.c reports usage of "ort" as "Merge made
by the 'ort' strategy" -- while it is meant as a drop in replacement for
"recursive" it is not yet treated as though it is recursive.  Update the
testcases to expect different output for the different merge backends.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>