Actioncable support is broken since 13.1

As part of !4152 (merged), we updated runit custom resources. But it seems we missed doing the same for actioncable related stuff. I tried enabling actioncable, and saw the following issues

1. down hasn't been replaced with start_down - https://gitlab.com/gitlab-org/omnibus-gitlab/blob/c780ffa74fcdab844c6af96dfc1adccbd5d1ab33/files/gitlab-cookbooks/gitlab/recipes/actioncable.rb#L82
2. Control files haven't been renamed - https://gitlab.com/gitlab-org/omnibus-gitlab/-/blob/c780ffa74fcdab844c6af96dfc1adccbd5d1ab33/files/gitlab-cookbooks/gitlab/templates/default/sv-actioncable-control-h.erb and https://gitlab.com/gitlab-org/omnibus-gitlab/-/blob/c780ffa74fcdab844c6af96dfc1adccbd5d1ab33/files/gitlab-cookbooks/gitlab/templates/default/sv-actioncable-control-t.erb