Remove environment variable that's no longer referenced
Remove environment variable that's no longer referenced

flag=none
closes MAT-617

test plan
- find an RCE and make sure it still works

Change-Id: Ieadc452d6a09cfed7d1fa94da1e4560e8d0139b3
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/284465
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: Jake Oeding <9601d161174d3602f0f7ee77da5115e75d23bb40@instructure.com>
QA-Review: Jake Oeding <9601d161174d3602f0f7ee77da5115e75d23bb40@instructure.com>
Product-Review: Jon Scheiding <9af6aa5061dd5eef0e85122953253a66930fcf3e@instructure.com>

sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms