leak tests: fix a memory leak in "test-progress" helper
Fix a memory leak in the test-progress helper, and mark the
corresponding "t0500-progress-display.sh" test as being leak-free
under SANITIZE=leak. This fixes a leak added in
2bb74b53a4 (Test the
progress display, 2019-09-16).
My
48f68715b14 (tr2: stop leaking "thread_name" memory, 2021-08-27)
had fixed another memory leak in this test (as it did some trace2
testing).
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>