update ar translation
update ar translation

Change-Id: I8ac29e292ff32a09bd95ac1875920ea683c344a1
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/224224
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>

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