Sidekiq 5.2.2 introduced a change
(https://github.com/mperham/sidekiq/pull/3936/files) that prevents queue
names from being duplicated. This breaks our current GitLab.com
config because we have some sidekiq-cluster processes configured
as the following:

```ruby
sidekiq_cluster['queue_groups'] = ["process_commit,process_commit"]
```

To keep things backwards compatible, we now only pass unique queue names
but scale the weights accordingly by the number of queues mentioned.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/54253