### 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/test/java/org/elasticsearch/cluster/routing/allocation/decider/DiskThresholdDeciderUnitTests.java
new ShardId(index, nodeShardCounter++),
                        true,
                        PeerRecoverySource.INSTANCE,
                        new UnassignedInfo(UnassignedInfo.Reason.INDEX_CREATED, "foo")
                    ),
                    nodeId
                );
                initializingShardSizes.put(ClusterInfo.shardIdentifierFromRouting(initializingShard), randomLongBetween(10, 50));
                shards.add(initializingShard);
            }
            
            if (randomBoolean()) {
                for (int j = 0; j < randomIntBetween(1, 5); j++) {
                    shards.add(createShard(anotherIndex, anotherNodeId, anotherNodeShardCounter++, expectedSize));
                }
            }
        }
        DiscoveryNode node = new DiscoveryNode(nodeId, buildNewFakeTransportAddress(), emptyMap(), emptySet(), Version.CURRENT);
        DiscoveryNode anotherNode = new DiscoveryNode(
            anotherNodeId,
            buildNewFakeTransportAddress(),
            emptyMap(),
            emptySet(),
            Version.CURRENT
        );
        ClusterState clusterState = ClusterState.builder(ClusterName.CLUSTER_NAME_SETTING.getDefault(Settings.EMPTY))
            .metadata(metadata)
            .routingTable(
                RoutingTable.builder()
                    .add(