### 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
.routingTable(routingTable)
            .build();
        clusterState = ClusterState.builder(clusterState).nodes(DiscoveryNodes.builder().add(node_0).add(node_1)).build();
        
        final long totalBytes = testMaxHeadroom ? ByteSizeValue.ofGb(10000).getBytes() : 100;
        Map<String, DiskUsage> leastAvailableUsages = Map.of("node_0", new DiskUsage("node_0", "node_0", "_na_", totalBytes, 0)); 
                                                                                                                                  
        final long freeBytes = testMaxHeadroom
            ? ByteSizeValue.ofGb(randomIntBetween(500, 10000)).getBytes()
            : randomLongBetween(50, totalBytes);
        Map<String, DiskUsage> mostAvailableUsage = Map.of("node_0", new DiskUsage("node_0", "node_0", "_na_", totalBytes, freeBytes));
        
        final long shardSize = randomLongBetween(totalBytes + 10, totalBytes * 10);
        ClusterInfo clusterInfo = new ClusterInfo(
            leastAvailableUsages,
            mostAvailableUsage,
            Map.of("[test][0][p]", shardSize),
            Map.of(),
            Map.of(),
            Map.of()
        );
        RoutingAllocation allocation = new RoutingAllocation(
            new AllocationDeciders(Collections.singleton(decider)),
            clusterState,
            clusterInfo,
            null,
            System.nanoTime()
        );
        allocation.debugDecision(true);
        Decision decision = decider.canAllocate(test_0, RoutingNodesHelper.routingNode("node_0", node_0), allocation);