### 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
}
    /**
     * Returns the shard size for the given shardId or <code>null</code> if that metric is not available.
     */
    public Long getShardSize(ShardId shardId, boolean primary) {
        return shardSizes.get(shardIdentifierFromRouting(shardId, primary));
    }
    /**
     * Returns the shard size for the given shard routing or <code>null</code> if that metric is not available.
     */
    public Long getShardSize(ShardRouting shardRouting) {
        return getShardSize(shardRouting.shardId(), shardRouting.primary());
    }
    /**
     * Returns the shard size for the given shard routing or <code>defaultValue</code> it that metric is not available.
     */
    public long getShardSize(ShardRouting shardRouting, long defaultValue) {
        Long shardSize = getShardSize(shardRouting);
        return shardSize == null ? defaultValue : shardSize;
    }
    /**
     * Returns the nodes absolute data-path the given shard is allocated on or <code>null</code> if the information is not available.
     */
    public String getDataPath(ShardRouting shardRouting) {
        return routingToDataPath.get(shardRouting);
    }
    public Optional<Long> getShardDataSetSize(ShardId shardId) {
        return Optional.ofNullable(shardDataSetSizes.get(shardId));
    }
    /**