add a domain suffix to newly generated lti tool_consumer_instance_guid

Change-Id: I243f56083e0e66fe0a21e415e02d573b9fc8bd76
Reviewed-on: https://gerrit.instructure.com/35148
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Clare Strong <clare@instructure.com>
Reviewed-by: Bracken Mosbacker <bracken@instructure.com>
Product-Review: Bracken Mosbacker <bracken@instructure.com>