### 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/ShardRouting.java
/**
     * Returns <code>true</code> if this shard is a relocation target for another shard
     * (i.e., was created with {@link #initializeTargetRelocatingShard()}
     */
    public boolean isRelocationTarget() {
        return state == ShardRoutingState.INITIALIZING && relocatingNodeId != null;
    }
    
    public boolean isRelocationTargetOf(ShardRouting other) {
        boolean b = this.allocationId != null
            && other.allocationId != null
            && this.state == ShardRoutingState.INITIALIZING
            && this.allocationId.getId().equals(other.allocationId.getRelocationId());
        assert b == false || other.state == ShardRoutingState.RELOCATING
            : "ShardRouting is a relocation target but the source shard state isn't relocating. This [" + this + "], other [" + other + "]";
        assert b == false || other.allocationId.getId().equals(this.allocationId.getRelocationId())
            : "ShardRouting is a relocation target but the source id isn't equal to source's allocationId.getRelocationId."
                + " This ["
                + this
                + "], other ["
                + other
                + "]";
        assert b == false || other.currentNodeId().equals(this.relocatingNodeId)
            : "ShardRouting is a relocation target but source current node id isn't equal to target relocating node."
                + " This ["
                + this
                + "], other ["
                + other
                + "]";
        assert b == false || this.currentNodeId().equals(other.relocatingNodeId)