lake: add Iceberg table docs

[awxxxxxx]

What is changed, added or deleted? (Required)

Rewrite the Apache Iceberg table documentation as a concise TiDB Cloud Lake reference:

• remove Datafuse/Databend, Docker, local environment, TPC-H, and concrete credential content
• remove quick starts, sample queries, command output, and example sections
• retain catalog syntax, connection parameters, supported catalog types, data type mappings, cache refresh, write syntax, and Iceberg table functions
• restore the Apache Iceberg page in the Table Engines overview and TiDB Cloud Lake TOC

The Iceberg entry was hidden in #23116 because the page still contained content that was not suitable for public TiDB Cloud Lake documentation. This PR cleans up that page before exposing the entry again.

Which TiDB version(s) do your changes apply to? (Required)

Tips for choosing the affected version(s):

By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.

For details, see tips for choosing the affected versions.

• master (the latest development version)
• v8.5 (TiDB 8.5 versions)
• v8.4 (TiDB 8.4 versions)
• v8.3 (TiDB 8.3 versions)
• v8.2 (TiDB 8.2 versions)
• v8.1 (TiDB 8.1 versions)
• v7.5 (TiDB 7.5 versions)
• v7.1 (TiDB 7.1 versions)
• v6.5 (TiDB 6.5 versions)

What is the related PR or file link(s)?

• This PR is translated from:
• Other reference link(s): lake: hide inapplicable entries and update branding names #23116

AI agent involvement

• The changes in this PR were primarily made by an AI agent on behalf of the PR author.

Do your changes match any of the following descriptions?

• Delete files
• Change aliases
• Need modification after applied to another branch
• Might cause conflicts after applied to another branch

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[gemini-code-assist]

Code Review

This pull request removes the Iceberg table engine option from the documentation on choosing a table engine in table-engines.md. There are no review comments, and I have no feedback to provide.

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