set dinghy env vars before checking them
set dinghy env vars before checking them

before running docker-machine inspect on DOCKER_MACHINE_NAME
run eval $(dinghy env) to ensure env vars are set. Also remove
unnecessary install variable getting set.

flag = none

Change-Id: I12a3106aeb4eae87fe411def204f1d05ca822780
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/259082
Reviewed-by: Andrea Cirulli <b4e55ef5ee4bae8ad31f7c81009bfc0af1714a1f@instructure.com>
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
QA-Review: James Butters <4c5a489c9bb72d41f20b3b22aaf4c9b864e32f20@instructure.com>
Product-Review: James Butters <4c5a489c9bb72d41f20b3b22aaf4c9b864e32f20@instructure.com>

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