script/autobuild.py: Restore MIT ADDC tests against fl2008*

script/autobuild.py: Restore MIT ADDC tests against fl2008*

Commit 7387da74e6f0e33de5f80b9a5e59f268541f52cd incorrectly
ran the fl2000dc and fl2003dc tests twice, rather than the
fl2008dc and fl2008r2dc tests in samba-ad-dc-4b-mitkrb5.

(Now ad-dc-mit-4b)

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14815

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Autobuild-User(master): Douglas Bagnall <dbagnall@samba.org>
Autobuild-Date(master): Thu Sep  2 05:56:12 UTC 2021 on sn-devel-184