fix data type in documentation and remove ssh tunnel for now

[jgao54]

Summary

• Discovered a few nuance with data types that needs to be fixed in docs.
• ssh tunnel not currently supported for MongoDB, remove for now.
• Remove the redundant title ClickPipes for MongoDB (and MySQL too):

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
clickhouse-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Aug 2, 2025 2:13am

3 Skipped Deployments

Name	Status	Preview	Comments	Updated (UTC)
clickhouse-docs-jp	⬜️ Ignored (Inspect)			Aug 2, 2025 2:13am
clickhouse-docs-ru	⬜️ Ignored (Inspect)	Visit Preview		Aug 2, 2025 2:13am
clickhouse-docs-zh	⬜️ Ignored (Inspect)	Visit Preview		Aug 2, 2025 2:13am

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}