Avoid deprecated extractor in StatusHandler

[sakshichitnis27]

Summary

• Replace the deprecated HttpMessageConverterExtractor usage in StatusHandler with local response body conversion.
• Preserve support for standard, generic, and smart message converters, including existing empty-body and error handling behavior.
• Add focused tests for the replacement conversion paths.

Testing

• ./gradlew :spring-web:test --tests org.springframework.web.client.StatusHandlerTests
• ./gradlew :spring-web:check

Closes #37010

[bclozel]

Thanks for the proposal @sakshichitnis27 - I went a different route in 51c4539 - instead of copying the now deprecated implementation, I extracted the relevant code from DefaultRestClient and shared it. This also aligns the behavior between proper body extraction and the status handler code path. Cheers!