Revert change to use the PSC for ClickHouse Cloud

What does this MR do?

Revert "Merge branch 'gprd-update-clickhouse-use-psc' into 'master'"

This reverts merge request !3145 (merged) because:

irb(main):001:0> ClickHouse::Client.select('SELECT 1', :main)
/srv/gitlab/lib/gitlab/http_connection_adapter.rb:60:in `rescue in validate_url_with_proxy!': URL is blocked: Requests to the local network are not allowed (Gitlab::HTTP_V2::BlockedUrlError)
/srv/gitlab/lib/gitlab/url_blocker.rb:327:in `validate_local_network': Requests to the local network are not allowed (Gitlab::HTTP_V2::UrlBlocker::BlockedUrlError)

Issue: https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/24569

Author Check-list

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• Check if all of the following apply:
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Applier Check-list

• Make sure there is no ongoing deployment for the affected envs before merging (see #announcements slack channel)