Remove FF_USE_GO_CLOUD_WITH_CACHE_ARCHIVER feature flag

Problem

In !2500 (merged) we introduced a new feature flag FF_USE_GO_CLOUD_WITH_CACHE_ARCHIVER since we introduced a new flag to the gitlab-runner-helper binary. This was required to prevent a breaking change in case users overridden the helper image.

Proposal

Remove the feature flag in %14.0