### 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
decision = decider.canRemain(indexMetadata, test_2, RoutingNodesHelper.routingNode("node_1", node_1), allocation);
        assertEquals("can stay since we don't have information about this shard", Decision.Type.YES, decision.type());
        assertThat(
            ((Decision.Single) decision).getExplanation(),
            containsString("this shard is not allocated on the most utilized disk and can remain")
        );
    }
    public void testCanRemainUsesLeastAvailableSpaceWithPercentages() {
        doTestCanRemainUsesLeastAvailableSpace(false);
    }
    public void testCanRemainUsesLeastAvailableSpaceWithMaxHeadroom() {
        doTestCanRemainUsesLeastAvailableSpace(true);
    }
    public void testShardSizeAndRelocatingSize() {
        Map<String, Long> shardSizes = new HashMap<>();
        shardSizes.put("[test][0][r]", 10L);
        shardSizes.put("[test][1][r]", 100L);
        shardSizes.put("[test][2][r]", 1000L);
        shardSizes.put("[other][0][p]", 10000L);
        ClusterInfo info = new DevNullClusterInfo(Map.of(), Map.of(), shardSizes);
        Metadata.Builder metaBuilder = Metadata.builder();
        metaBuilder.put(
            IndexMetadata.builder("test")
                .settings(settings(Version.CURRENT).put("index.uuid", "1234"))
                .numberOfShards(3)
                .numberOfReplicas(1)
        );
        metaBuilder.put(
            IndexMetadata.builder("other")
                .settings(settings(Version.CURRENT).put("index.uuid", "5678"))