fix: doc: Remove the CHANGES file

With the introduction of the generated changelog, the CHANGES file became a symlink to doc/arm/changelog.rst. After the changes made in !9549 (merged), the changelog file transitioned from being a wholly generated file to one that includes versioned changelog files, which are themselves generated. However, while implementing !9549 (merged), we overlooked that the CHANGES file is copied to a release directory on an FTP server and contains just "include" directives, not the changelog itself. Therefore, in the same fashion as the "RELEASE-NOTES*.html" file, create a "CHANGELOG*.html" file that redirects to the Changelog appendix of the ARM.

Closes #5000