Integrations: landing page revamp

[Blargian]

Summary

Changes introduced in #4477. Reverted as some links needed to be fixed in the CMS first. Also added a fallback mechanism so that if the CMS endpoint is inaccessible it will fall back to a static version kept in the docs repo.

Checklist

• Delete items not relevant to your PR
• URL changes should add a redirect to the old URL via https://github.com/ClickHouse/clickhouse-docs/blob/main/docusaurus.config.js
• If adding a new integration page, also add an entry to the integrations list here: https://github.com/ClickHouse/clickhouse-docs/blob/main/docs/integrations/index.mdx

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