bpo-34171: Fix test_trace. (GH-8940) (GH-8951)

Remove "trace.cover" left from previous test runs before testing
that it is no longer created.
(cherry picked from commit b44a1d4f71daf4edb948b9878f82a60891e4a2e1)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
1 file changed