ls-remote & transport API: release "struct transport_ls_refs_options"

ls-remote & transport API: release "struct transport_ls_refs_options"

Fix a memory leak in codepaths that use the "struct
transport_ls_refs_options" API. Since the introduction of the struct
in 39835409d10 (connect, transport: encapsulate arg in struct,
2021-02-05) the caller has been responsible for freeing it.

That commit in turn migrated code originally added in
402c47d9391 (clone: send ref-prefixes when using protocol v2,
2018-07-20) and b4be74105fe (ls-remote: pass ref prefixes when
requesting a remote's refs, 2018-03-15). Only some of those codepaths
were releasing the allocated resources of the struct, now all of them
will.

Mark the "t/t5511-refspec.sh" test 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). Previously 24/47 tests would fail.

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