t6404, t6423: expect improved rename/delete handling in ort backend

t6404, t6423: expect improved rename/delete handling in ort backend

When a file is renamed and has content conflicts, merge-recursive does
not have some stages for the old filename and some stages for the new
filename in the index; instead it copies all the stages corresponding to
the old filename over to the corresponding locations for the new
filename, so that there are three higher order stages all corresponding
to the new filename.  Doing things this way makes it easier for the user
to access the different versions and to resolve the conflict (no need to
manually 'git rm' the old version as well as 'git add' the new one).

rename/deletes should be handled similarly -- there should be two stages
for the renamed file rather than just one.  We do not want to
destabilize merge-recursive right now, so instead update relevant tests
to have different expectations depending on whether the "recursive" or
"ort" merge strategies are in use.

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