### 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
test_3 = ShardRoutingHelper.initialize(test_3, node_1.getId());
        test_3 = ShardRoutingHelper.moveToStarted(test_3);
        
        RoutingTable routingTable = RoutingTable.builder().addAsNew(indexMetadata).build();
        ClusterState clusterState = ClusterState.builder(
            org.elasticsearch.cluster.ClusterName.CLUSTER_NAME_SETTING.getDefault(Settings.EMPTY)
        ).metadata(metadata).routingTable(routingTable).build();
        logger.info("--> adding two nodes");
        clusterState = ClusterState.builder(clusterState).nodes(DiscoveryNodes.builder().add(node_0).add(node_1)).build();
        
        final long totalBytes = testMaxHeadroom ? ByteSizeValue.ofGb(10000).getBytes() : 100;
        final long exactFreeSpaceForHighWatermark = testMaxHeadroom ? ByteSizeValue.ofGb(150).getBytes() : 10;
        final long exactFreeSpaceForBelowHighWatermark = exactFreeSpaceForHighWatermark - 1;
        final double exactUsedSpaceForBelowHighWatermark = 100.0 * (totalBytes - exactFreeSpaceForBelowHighWatermark) / totalBytes;
        final long ninetyPercentFreeSpace = (long) (totalBytes * 0.9);
        Map<String, DiskUsage> leastAvailableUsages = new HashMap<>();
        leastAvailableUsages.put("node_0", new DiskUsage("node_0", "node_0", "/node0/least", totalBytes, exactFreeSpaceForHighWatermark));
        leastAvailableUsages.put(
            "node_1",
            new DiskUsage("node_1", "node_1", "/node1/least", totalBytes, exactFreeSpaceForBelowHighWatermark)
        );
        Map<String, DiskUsage> mostAvailableUsage = new HashMap<>();
        mostAvailableUsage.put("node_0", new DiskUsage("node_0", "node_0", "/node0/most", totalBytes, ninetyPercentFreeSpace));
        mostAvailableUsage.put("node_1", new DiskUsage("node_1", "node_1", "/node1/most", totalBytes, ninetyPercentFreeSpace));
        Map<String, Long> shardSizes = new HashMap<>();
        shardSizes.put("[test][0][p]", exactFreeSpaceForHighWatermark);
        shardSizes.put("[test][1][p]", exactFreeSpaceForHighWatermark);
        shardSizes.put("[test][2][p]", exactFreeSpaceForHighWatermark);
        final ClusterInfo clusterInfo = new ClusterInfo(
            leastAvailableUsages,