Bulk add bad default auth_setting

[jorwoods]

server-client-python/tableauserverclient/server/request_factory.py

Line 1000 in ec0614e

user_element.attrib["authSetting"] = user.auth_setting or "ServerDefault"

"ServerDefault" is the correct default auth_setting for a Server instance, but it is the incorrect default for a Cloud instance. This is yet another reason why something like #1592 is needed because of differences between Server and Cloud.

[jacalata]

Fixed in #1779 — changed the bulk add request to only send authSetting when explicitly set, matching the existing behaviour in single-user add/update.