load integration_id from user CSV file

fixes SIS-661

Test plan:
- confirm integration_id is now being loaded from user csv
- specs pass

Change-Id: Ie47c1bf9420871b1a017ebc0352d968e1564dda7
Reviewed-on: https://gerrit.instructure.com/45121
Reviewed-by: Ken Romney <kromney@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Jeremy Putnam <jeremyp@instructure.com>
Product-Review: Cosme Salazar <cosme@instructure.com>