Remove unnecessary H1 headers

[Blargian]

Summary

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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Note

Low Risk
Documentation-only formatting and title metadata changes with no application or security impact.

Overview
This PR removes redundant in-page # H1 headings across a large set of documentation pages so the site title comes from frontmatter title (and Docusaurus rendering) instead of duplicating the headline in the body.

On many pages the frontmatter title was also updated to clearer or title-case wording (for example SQL Console, Prometheus Integration, migration guide titles). A few non-heading fixes appear in the same diff: Paimon settings links in beta-and-experimental-features.md, a changelog TOC row reorder in docs/cloud/reference/01_changelog/02_release_notes/index.md, and a heading level tweak in 24_05.md.

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