### 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
Metadata metadata,
        RoutingTable routingTable
    ) {
        final IndexMetadata indexMetadata = metadata.getIndexSafe(shard.index());
        if (indexMetadata.getResizeSourceIndex() != null
            && shard.active() == false
            && shard.recoverySource().getType() == RecoverySource.Type.LOCAL_SHARDS) {
            
            
            long targetShardSize = 0;
            final Index mergeSourceIndex = indexMetadata.getResizeSourceIndex();
            final IndexMetadata sourceIndexMeta = metadata.index(mergeSourceIndex);
            if (sourceIndexMeta != null) {
                final Set<ShardId> shardIds = IndexMetadata.selectRecoverFromShards(
                    shard.id(),
                    sourceIndexMeta,
                    indexMetadata.getNumberOfShards()
                );
                final IndexRoutingTable indexRoutingTable = routingTable.index(mergeSourceIndex.getName());
                for (int i = 0; i < indexRoutingTable.size(); i++) {
                    IndexShardRoutingTable shardRoutingTable = indexRoutingTable.shard(i);
                    if (shardIds.contains(shardRoutingTable.shardId())) {
                        targetShardSize += clusterInfo.getShardSize(shardRoutingTable.primaryShard(), 0);
                    }
                }
            }
            return targetShardSize == 0 ? defaultValue : targetShardSize;
        } else {
            if (shard.unassigned() && shard.recoverySource().getType() == RecoverySource.Type.SNAPSHOT) {
                return snapshotShardSizeInfo.getShardSize(shard, defaultValue);