use api find for files show fixes bad users.id query 

refs CNVS-4747

Change-Id: I8aeefb9c14e6450238c34c29e5dc87984aeec6a2
Reviewed-on: https://gerrit.instructure.com/31702
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: Rob Orton <rob@instructure.com>
QA-Review: Rob Orton <rob@instructure.com>