Fix type-checking errors in snippets (code only, no .md)

This commit both:
- Fixes pre-existing mistakes in snippets, aka wrong code samples.
- Adds hidden (`@hide`) statements that do not appear in the docs,
  but satisfy typecheckers.

qdrant-landing/content/documentation/headless/snippets/update-collection/trigger-indexing/go.go

@@ -12,6 +12,8 @@ func Main() {
 		Port: 6334,
 	})
 
+	if err != nil { panic(err) } // @hide
+
 	client.UpdateCollection(context.Background(), &qdrant.UpdateCollection{
 		CollectionName:   "{collection_name}",
 		OptimizersConfig: &qdrant.OptimizersConfigDiff{},

qdrant-landing/content/documentation/headless/snippets/update-collection/trigger-indexing/java.java

@@ -5,6 +5,11 @@ import io.qdrant.client.grpc.Collections.UpdateCollection;
 
 public class Snippet {
         public static void run() throws Exception {
+                // @hide-start
+                io.qdrant.client.QdrantClient client =
+                    new io.qdrant.client.QdrantClient(io.qdrant.client.QdrantGrpcClient.newBuilder("localhost", 6334, false).build());
+                // @hide-end
+
                 client.updateCollectionAsync(
                     UpdateCollection.newBuilder()
                         .setCollectionName("{collection_name}")

qdrant-landing/content/documentation/headless/snippets/update-collection/trigger-indexing/rust.rs

@@ -1,6 +1,8 @@
 use qdrant_client::qdrant::{OptimizersConfigDiffBuilder, UpdateCollectionBuilder};
 
 pub async fn main() -> anyhow::Result<()> {
+    let client = qdrant_client::Qdrant::from_url("http://localhost:6334").build()?; // @hide
+
     client
         .update_collection(
             UpdateCollectionBuilder::new("{collection_name}")