Improve `refer_URL` path to SaaS /checkout
Following discussion in https://gitlab.com/gitlab-data/product-analytics/-/issues/425#note_928260303 and analysis (https://app.periscopedata.com/app/gitlab:safe-dashboard/985319/SaaS-Purchase-Flow-Funnel-(via-Billings-page)?widget=14474845&udv=1568345). We want to take steps to improve the refer_URL
path for users navigating to the SaaS /checkout page.
Edited by Gayle Doud