spec: Fix flaky specs in courses_spec.rb
spec: Fix flaky specs in courses_spec.rb

closes: ADMIN-2993

Improved the waiting around page gets and finds

Change-Id: Ice4b8813bc76438936817332be8f2550d2b2df97
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/213277
Tested-by: Jenkins
Reviewed-by: KC Naegle <9fbecd016338f9910821a8a5d5d0ae4fc9abfaa5@instructure.com>
QA-Review: KC Naegle <9fbecd016338f9910821a8a5d5d0ae4fc9abfaa5@instructure.com>
Product-Review: KC Naegle <9fbecd016338f9910821a8a5d5d0ae4fc9abfaa5@instructure.com>

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