python/samba/tests: Remove DCs joined to test samba-tool behaviour

python/samba/tests: Remove DCs joined to test samba-tool behaviour

Otherwise we have the live DCs spamming the logs looking for the
long-gone test servers:

Failed to connect host fd00::5357:5f0b on port 135 - NT_STATUS_OBJECT_NAME_NOT_FOUND
Failed to connect host fd00::5357:5f0b (6f44653d-18c8-4bf4-b2e7-6f85cf7b0f74._msdcs.addom.samba.example.com) on port 135 - NT_STATUS_OBJECT_NAME_NOT_FOUND.
Failed to connect host 10.53.57.11 on port 135 - NT_STATUS_OBJECT_NAME_NOT_FOUND
Failed to connect host 10.53.57.11 (6f44653d-18c8-4bf4-b2e7-6f85cf7b0f74._msdcs.addom.samba.example.com) on port 135 - NT_STATUS_OBJECT_NAME_NOT_FOUND.
Failed to connect host 10.53.57.12 on port 135 - NT_STATUS_OBJECT_NAME_NOT_FOUND

This avoids spamming the GitLab pipeline logs with a lot of noise,
as there is a size limit to the output, as well as being cleaner.

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>