This commit adds a "cache bust" for the keys used in the
ReleaseHighlight model. Following a staging deploy it became aparent
that the type of object returned by the cache did not match the
previous, which was causing 500's.

part of:
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/49233
https://gitlab.com/gitlab-com/gl-infra/production/-/issues/3144
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/47852