Announce debusine.debian.net on debian-devel-announce

Shortly after the release of Debian trixie we want to officially announce the availability of debusine.debian.net to upload to unstable and have some quick feedback on your upload, including autopkgtest of reverse dependencies.

Before sending the announce, we want to ensure that #973 (closed) has been fixed so that reverse autopkgtest do not overload the workers and that DD have at least quick feedback on builds and usual QA tasks. We also want to document that the service is also available to Debian maintainers, and that there are limitations in account synchronizations (cf #977 (closed)).

• Ensure #973 (closed) and #977 (closed) are fixed
• Prepare the announce
• Send the announce on August 11th