If restarted in pause Patroni was discarding `synchronous_standby_names` from `postgresql.conf` because in the internal cache this values was set to `None`. As a result synchronous replication transitioned to a broken state, with no synchronous replicas according to the `synchronous_standby_names` and Patroni not selecting/setting the new synchronous replicas (another bug).
To solve the problem of broken initial state and to avoid similar issues with other GUC's we will read GUC's value if Patroni is joining running Postgres.