don't update Zendesk user for change user requests

change user requests may not have the full user details, so
we might lose information if we write to Zendesk
don't ask about roles for "remove user" requests

asking about roles doesn't really make sense. Generally the request is when
the user leaves an organisation completely, and there's now an alternative
path for requesting changes to permissions.
Merge remote-tracking branch 'origin/dont-update-zendesk-user-for-change-user-requests'
Merge remote-tracking branch 'origin/remove-user-requests-dont-ask-user-about-tool-role'