leak tests: mark some read-tree tests as passing with SANITIZE=leak

leak tests: mark some read-tree tests as passing with SANITIZE=leak

Mark some tests that match "*read-tree*" as passing when git is
compiled with SANITIZE=leak. They'll now be listed as running under
the "GIT_TEST_PASSING_SANITIZE_LEAK=true" test mode (the "linux-leaks"
CI target). We still have around half the tests that match
"*read-tree*" failing, but let's whitelist those that don't.

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