docs: port TLS settings docs for DB ClickPipes (PR #6421)

[mintlify]

Summary

Ports upstream clickhouse-docs#6421 (TLS Unification in DB ClickPipes) to the Mintlify docs.

Changes

• Added shared snippet snippets/clickpipes/_changing_tls_settings.mdx describing default TLS behaviour, where to change settings (creation flow + paused pipe's Connection settings), and the meaning of Disable TLS, Skip certificate verification, TLS Host, and Upload CA.
• Imported the snippet in the Postgres, MySQL, and MongoDB ClickPipes index pages under a new (Optional) Changing TLS settings section (after AWS Private Link for Postgres, after connection details and before SSH tunneling for MySQL/MongoDB).
• Copied 3 new screenshots into images/integrations/data-ingestion/clickpipes/postgres/ (tls-settings.png, pipe-connection-settings.png, pipe-edit-connection.png).

Context

Transformed Docusaurus-style @site/... imports + @theme/IdealImage into Mintlify equivalents (/snippets/... paths, shared Image component). Slugs of the three index pages are preserved. No ambiguities encountered.

[mintlify]

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Project	Status	Preview	Updated (UTC)
ClickHouse-docs	🟢 Ready	View Preview	Jun 23, 2026, 9:37 AM

[Blargian]

@copilot resolve the merge conflicts in this pull request

[Copilot]

@copilot resolve the merge conflicts in this pull request

Resolved. The only conflicts were binary add/add conflicts in the 3 PNG screenshots (both this branch and main had added the same images). Kept main's versions (which were optimized — ~64% smaller). All TLS settings documentation changes (snippet + postgres/mysql/mongodb index pages) are preserved intact.

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