allow local file store to redirect

closes CNVS-15397

when canvas is configured to use the local file store, it will always
redirect after the upload happens. allow for this, while still making S3
uploads not auto-redirect (to avoid CORS errors)

test plan:
  - enable new files
  - configure local uploads
    - verify you can successfully upload a file
  - configure S3 uploads (with CORS configured to accept 'content-type'
    headers)
    - verify you can successfully upload a file

Change-Id: Idcbeb1b5f37e88d64e130bb0496eaf3bc231f426
Reviewed-on: https://gerrit.instructure.com/40848
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Clay Diffrient <cdiffrient@instructure.com>
Reviewed-by: Ryan Shaw <ryan@instructure.com>
Product-Review: Jason Madsen <jmadsen@instructure.com>
QA-Review: Jason Madsen <jmadsen@instructure.com>