test: lister_test: test_directory_lister_close simplify indentation
test: lister_test: test_directory_lister_close simplify indentation

There's no need anymore for an indented block
to destroy tnhe directory_lister since the other
sub-case was deleted.

Signed-off-by: Benny Halevy <23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla