Update release notes for v25.4-v25.4.0-cloudonly.1

Author: Automated Release Bot

src/current/_includes/releases/v25.4/v25.4.0-cloudonly.1.md

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+## v25.4.0-cloudonly.1
+
+Release Date: November 3, 2025
+
+{% include releases/new-release-downloads-docker-image.md release=include.release %}
+
+<h3 id="v25-4-0-cloudonly-1-sql-language-changes">SQL language changes</h3>
+
+- Vector indexing is now enabled by default. [#155561][#155561]
+
+
+[#155561]: https://github.com/cockroachdb/cockroach/pull/155561