Search block: Update docs with removed attributes

[cbravobernal]

What?

Remove not used params in render_block_core_search function. Added a removal comment.

Why?

Requested in WordPress/wordpress-develop#5922 (comment)

Testing Instructions

• Add a filter to render_block_core_search or replace and use $block or $content. They should still be available in your functions.

[github-actions]

Flaky tests detected in 38989b4.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/7699068037
📝 Reported issues:

• [Flaky Test] directives inside islands should not be hydrated twice #58332 in /test/e2e/specs/interactivity/tovdom-islands.spec.ts

[cbravobernal]

Close as duplicated.