Replace clickhouse_ci_analytics FF with database config check

What does this MR do and why?

Draft: Replace clickhouse_ci_analytics FF with database config check

We want to make it easier to set up clickhouse analytics database. To do that we need to remove some feature flags from https://gitlab.com/gitlab-org/gitlab/blob/5f571d8c9c7682c126f91a68010728203f25486c/doc/ci/runners/runner_fleet_dashboard.md#L47

This MR replaces the clickhouse_ci_analytics with the check on the ClickHouse database being available.

Related issue: clickhouse_ci_analytics Rollout clickhouse_ci_a... (#424498 - closed)

Changelog: added

MR acceptance checklist

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Screenshots or screen recordings

No visual difference

How to set up and validate locally

1. Configure ClickHouse with gdk https://docs.gitlab.com/ee/development/database/clickhouse/clickhouse_within_gitlab.html#gdk-setup (don't forget to run migrations)
2. Go to Admin area -> Runners -> Runner Fleet dashboard
3. See this:
4. If you remove the ClickHouse config and restart the gdk, then the bottom chart will disappear.