As the milestone builds are no longer available, how can I update my 2.5.0RC1 release to the latest 2.5 release on CentOS (yum based)
You should be able to update by changing to the stable repository first.
I just changed the following part in /etc/yum.repos.d/openhab.repo
I remember the last time I changed the whole content in the file, openhab-testing was removed and openhab-stable was then freshly installed and I had to restore all my settings from the backup.
This way, the update kept all the configurations.