ESQL does not support cross-cluster search yet; when a CCS pattern is used in a FROM command, the error message is not very clear for the end user

<img width="590" alt="Screenshot 2023-11-27 alle 15 38 02" src="https://github.com/elastic/elasticsearch/assets/459289/5af48932-4a4c-416a-a926-7bd486d282a5">

We should make it more user friendly
x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/plugin/ComputeService.java
if (group.allocatedNodes().isEmpty()) {
                        throw new ShardNotFoundException(group.shardId(), "no shard copies found {}", group.shardId());
                    }
                    if (concreteIndices.contains(shardId.getIndexName()) == false) {
                        continue;
                    }
                    String targetNode = group.allocatedNodes().get(0);
                    nodeToShards.computeIfAbsent(targetNode, k -> new ArrayList<>()).add(shardId);
                    AliasFilter aliasFilter = resp.getAliasFilters().get(shardId.getIndex().getUUID());
                    if (aliasFilter != null) {
                        nodeToAliasFilters.computeIfAbsent(targetNode, k -> new HashMap<>()).put(shardId.getIndex(), aliasFilter);
                    }
                }
                List<TargetNode> targetNodes = new ArrayList<>(nodeToShards.size());
                for (Map.Entry<String, List<ShardId>> e : nodeToShards.entrySet()) {
                    DiscoveryNode node = nodes.get(e.getKey());
                    Map<Index, AliasFilter> aliasFilters = nodeToAliasFilters.getOrDefault(e.getKey(), Map.of());
                    targetNodes.add(new TargetNode(node, e.getValue(), aliasFilters));
                }
                return targetNodes;
            }),
            threadContext
        );
        try (ThreadContext.StoredContext ignored = threadContext.newStoredContextPreservingResponseHeaders()) {
            threadContext.markAsSystemContext();
            SearchShardsRequest searchShardsRequest = new SearchShardsRequest(
                originalIndices,
                SearchRequest.DEFAULT_INDICES_OPTIONS,
                filter,
                null,