Fix Sidekiq system check for cluster mode

What does this MR do?

When running with sidekiq-cluster (which is the default now) we have more than one worker process, so the check is changed to either require 0 cluster processes and 1 worker, or 1 cluster process with 1+ workers.

Replaces the original MR !50873 (closed) contributed by @prote.

Fixes #295665 (closed)

Running without a cluster is deprecated and will be removed in %14.0: https://gitlab.com/gitlab-org/gitlab/-/blob/master/doc/install/installation.md#using-sidekiq-instead-of-sidekiq-cluster

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