### Description

It should be enough to have ShardId + nodeId key in `routingToDataPath` to find the necessary data path. 
Changing the key would allow us to minimize the size of ClusterInfo size and find the data path when shard changes its status.

`ClusterInfo` might be sent over the wire when cluster allocation explain is executed with `includeDiskInfo=true`.
ShardRouting -> ShardId + nodeId conversion is trivial. The oposit would require additional information that could be faked.

Current key is also used in here:
https://github.com/elastic/elasticsearch/blob/9ebbe1c62bf0157d332f20f392544a1921a710df/server/src/main/java/org/elasticsearch/cluster/ClusterInfo.java#L149-L154
where it produces a string with ShardRouting#shortSummary that is excessive and might be simplified to ShardId + nodeId as well
server/src/main/java/org/elasticsearch/cluster/ClusterInfo.java
import java.util.Objects;
import java.util.Optional;
import java.util.Set;
/**
 * ClusterInfo is an object representing a map of nodes to {@link DiskUsage}
 * and a map of shard ids to shard sizes, see
 * <code>InternalClusterInfoService.shardIdentifierFromRouting(String)</code>
 * for the key used in the shardSizes map
 */
public class ClusterInfo implements ToXContentFragment, Writeable {
    public static final ClusterInfo EMPTY = new ClusterInfo();
    public static final Version DATA_SET_SIZE_SIZE_VERSION = Version.V_7_13_0;
    private final Map<String, DiskUsage> leastAvailableSpaceUsage;
    private final Map<String, DiskUsage> mostAvailableSpaceUsage;
    final Map<String, Long> shardSizes;
    final Map<ShardId, Long> shardDataSetSizes;
    final Map<ShardRouting, String> routingToDataPath;
    final Map<NodeAndPath, ReservedSpace> reservedSpace;
    protected ClusterInfo() {
        this(Map.of(), Map.of(), Map.of(), Map.of(), Map.of(), Map.of());
    }
    /**
     * Creates a new ClusterInfo instance.
     *
     * @param leastAvailableSpaceUsage a node id to disk usage mapping for the path that has the least available space on the node.
     * @param mostAvailableSpaceUsage  a node id to disk usage mapping for the path that has the most available space on the node.
     * @param shardSizes a shardkey to size in bytes mapping per shard.
     * @param shardDataSetSizes a shard id to data set size in bytes mapping per shard
     * @param routingToDataPath the shard routing to datapath mapping
     * @param reservedSpace reserved space per shard broken down by node and data path