Improve KRaft metadata image change performance at high topic counts

Performance of KRaft metadata image changes is currently O(<# of topics in cluster>). This means the amount of time it takes to create just a single topic scales linearly with the number of topics in the entire cluster. This impact both controllers and brokers because both use the metadata image to represent the KRaft metadata log. The performance of these changes should scale with the number of topics being changed – so creating a single topic should perform similarly regardless of the number of topics in the cluster.