### 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/InternalClusterInfoService.java
reservedSpaceBuilder.add(shardRouting.shardId(), reserved);
            }
        }
    }
    private static void fillDiskUsagePerNode(
        List<NodeStats> nodeStatsArray,
        Map<String, DiskUsage> newLeastAvailableUsages,
        Map<String, DiskUsage> newMostAvailableUsages
    ) {
        for (NodeStats nodeStats : nodeStatsArray) {
            DiskUsage leastAvailableUsage = DiskUsage.findLeastAvailablePath(nodeStats);
            if (leastAvailableUsage != null) {
                newLeastAvailableUsages.put(nodeStats.getNode().getId(), leastAvailableUsage);
            }
            DiskUsage mostAvailableUsage = DiskUsage.findMostAvailable(nodeStats);
            if (mostAvailableUsage != null) {
                newMostAvailableUsages.put(nodeStats.getNode().getId(), mostAvailableUsage);
            }
        }
    }
    private record IndicesStatsSummary(
        Map<String, Long> shardSizes,
        Map<ShardId, Long> shardDataSetSizes,
        Map<ShardRouting, String> shardRoutingToDataPath,
        Map<ClusterInfo.NodeAndPath, ClusterInfo.ReservedSpace> reservedSpace
    ) {
        static final IndicesStatsSummary EMPTY = new IndicesStatsSummary(Map.of(), Map.of(), Map.of(), Map.of());
    }
}