[watcher] Unmaintained branch cleanup

Hi everyone, Watcher currently has two unmaintained branches[1], unmaintained/2024.1 and unmaintained/2023.1. The latter has not had any patch in 2 years [2] so we plan to move it to eol. We will discuss it in the next Watcher IRC meeting, but I'm writing this message early to give everyone a chance to raise any objection. Please respond to this message if you have any objection, if there are none, I will propose a patch to move the branch next Thursday, after the Watcher IRC meeting and share the link here. Regards, Joan [1] https://opendev.org/openstack/watcher/branches [2] https://opendev.org/openstack/watcher/commits/branch/unmaintained/2023.1