void writeReindexingStatus(ApplicationId id, ApplicationReindexing status) {
        curator.set(reindexingDataPath(id), ReindexingStatusSerializer.toBytes(status));
    }
List the active applications of a tenant in this config server.

@return a list of {@link ApplicationId}s that are active.
configserver/src/main/java/com/yahoo/vespa/config/server/application/ApplicationCuratorDatabase.java