leak tests: mark a read-tree test as passing SANITIZE=leak

The "t1002-read-tree-m-u-2way.sh" test has passed under SANITIZE=leak
since 04988c8d18 (unpack-trees: introduce preserve_ignored to
unpack_trees_options, 2021-09-27) was combined with
e5a917fcf4 (unpack-trees: don't leak memory in
verify_clean_subdirectory(), 2021-10-07), but as both were in-flight
at the time neither could mark it as passing.

It will now be listed as running under the
"GIT_TEST_PASSING_SANITIZE_LEAK=true" test mode (the "linux-leaks" CI
target).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1002-read-tree-m-u-2way.sh

@@ -8,6 +8,8 @@ test_description='Two way merge with read-tree -m -u $H $M
 This is identical to t1001, but uses -u to update the work tree as well.
 
 '
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-read-tree.sh