### 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
if (logger.isDebugEnabled()) {
                    logger.debug(
                        "less than the required {} free bytes threshold ({} free) on node {}, "
                            + "preventing allocation even though primary has never been allocated",
                        diskThresholdSettings.getFreeBytesThresholdHighStage(total).getBytes(),
                        freeBytesValue,
                        node.nodeId()
                    );
                }
                return allocation.decision(
                    Decision.NO,
                    NAME,
                    "the node is above the high watermark cluster setting [%s], having less than the minimum required [%s] free "
                        + "space, actual free: [%s], actual used: [%s]",
                    diskThresholdSettings.describeHighThreshold(total, true),
                    diskThresholdSettings.getFreeBytesThresholdHighStage(total),
                    freeBytesValue,
                    Strings.format1Decimals(usedDiskPercentage, "%")
                );
            }
        }
        
        final long shardSize = getExpectedShardSize(
            shardRouting,
            0L,
            allocation.clusterInfo(),
            allocation.snapshotShardSizeInfo(),
            allocation.metadata(),