### 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/routing/allocation/decider/DiskThresholdDecider.java
usage.getFreeDiskAsPercentage()
            );
        }
        final DiskUsageWithRelocations diskUsageWithRelocations = new DiskUsageWithRelocations(
            usage,
            sizeOfUnaccountedShards(
                node,
                subtractLeavingShards,
                usage.getPath(),
                allocation.clusterInfo(),
                allocation.metadata(),
                allocation.routingTable(),
                allocation.unaccountedSearchableSnapshotSize(node)
            )
        );
        logger.trace("getDiskUsage(subtractLeavingShards={}) returning {}", subtractLeavingShards, diskUsageWithRelocations);
        return diskUsageWithRelocations;
    }
    /**
     * Returns a {@link DiskUsage} for the {@link RoutingNode} using the
     * average usage of other nodes in the disk usage map.
     * @param node Node to return an averaged DiskUsage object for
     * @param usages Map of nodeId to DiskUsage for all known nodes
     * @return DiskUsage representing given node using the average disk usage
     */
    static DiskUsage averageUsage(RoutingNode node, Map<String, DiskUsage> usages) {
        if (usages.size() == 0) {
            return new DiskUsage(node.nodeId(), node.node().getName(), "_na_", 0, 0);
        }
        long totalBytes = 0;