S3 releases not uploading on master

Overview

Latest pipelines that release bleeding edge to s3 bucket are not being uploaded for example in https://gitlab.com/gitlab-org/gitlab-runner/-/jobs/421589994 notice how ==> Download index file: https://gitlab-runner-downloads.s3.amazonaws.com//index.html the link should be https://gitlab-runner-downloads.s3.amazonaws.com/master/index.html.

In !1803 (merged) we introduced a change in ci/release_s3 with a small bug which was fixed in !1807 (merged) but the URL is still incorrect.