Change mount of secret with S3 distributed cache credentials
This merge reuest contains some changes from https://gitlab.com/charts/gitlab-runner/merge_requests/49 that decided to make as separate MR to avoid braking changes.
For my opinion this changes doesn't break backward compatibility, cause it doesn't changes configuration format, it's only changes mount points. So with this change user can upgrade chart without changing any values.
Edited by Dmitry Chepurovskiy