Investigate oddities in the configuration properties changelog

[wilkinsona]

https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-4.0.0-M1-Configuration-Changelog

There are some properties without descriptions and also some that are reported as having been removed when they have not been.

[snicoll]

The HTTP client properties missed some of the documentation due to org.springframework.boot.http.client.autoconfigure.AbstractHttpRequestFactoryProperties not being flagged a @ConfigurationPropertiesSource.

[snicoll]

We should probably add a note for the Wavefront-related properties.

[snicoll]

So #46536 fixed part of it. Configuration metadata wasn't enabled for the web client modules we added recently. Once I did that, the build started to fail with the missing descriptions.