Registry: Add support for Redis cluster addresses

While testing the Redis rate-limiting configuration on pre, we hound that the chart will append a port to the last host on a list like the following:

values.yml:

  redis:
    rateLimiting:
      enabled: true
      host: 'redis.one.example.com:6379, redis.two.example.com:6379'

Rendered configuration:

    redis:
      ratelimiter:
        enabled: true
        addr: "redis.one.example.com:6379, redis.two.example.com:6379:6379"

See gitlab-com/gl-infra/k8s-workloads/gitlab-com!3727 (merged).

This will allow to specify a Redis cluster rather than a single host or Sentinels