With the new release identification / naming schema [1] (like:
2023.1 Antelope) new stable branch naming was introduced (like:
stable/2023.1). This was not handled in the propose-library-branches
command as it still used the release name. This patch fixes this by
reading the 'release-id' field from series_status.yaml and if
present then uses it as stable/<release-id> for the branch creation.
[1] https://governance.openstack.org/tc/reference/release-naming.html
Change-Id: Ie87862669fb965729e23a9374c34b1ba2e71b445