run-aa-test: Fix call to csplit

New version of `csplit` from `rust-coreutils` fails with following error:
  $ csplit R1.13a.1_bluez-spp.expected -f /tmp/EXPECT -b "%d" "/^## alternative ##$/" {*}
  csplit: error: incorrect conversion specification in suffix

Replacing `%d` by `%0d` fixes it.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>