managerd: fix ref used on successful upgrade

AUM does not set the right refs to the repo commit when the upgrade contains development and release entries in its ref-bindings, e.g. it will use v2022dev3 instead of v2022 if both are present.

When adding ref-bindings to a commit, OSTree sort them in default alphabetic order using strcmp().

This commit looks for the correct ref for the repo commit.

https://phabricator.apertis.org/T8609

Signed-off-by: Frédéric Danis frederic.danis@collabora.com