update ar translation
update ar translation

Change-Id: Icab426662997ecc6c60908409d68c9ef1e3e29b4
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/304883
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>

instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms