t: mark several submodule merging tests as fixed under merge-ort

t: mark several submodule merging tests as fixed under merge-ort

merge-ort handles submodules (and directory/file conflicts in general)
differently than merge-recursive does; it basically puts all the special
handling for different filetypes into one place in the codebase instead
of needing special handling for different filetypes in many different
code paths.  This one code path in merge-ort could perhaps use some work
still (there are still test_expect_failure cases in the testsuite), but
it passes all the tests that merge-recursive does as well as 12
additional ones that merge-recursive fails.  Mark those 12 tests as
test_expect_success under merge-ort.

Signed-off-by: Elijah Newren <newren@gmail.com>
Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>