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/set-payload/by-filter/go.go

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

qdrant-landing/content/documentation/headless/snippets/set-payload/by-filter/java.java

@@ -3,10 +3,16 @@ package com.example.snippets_amalgamation;
 import static io.qdrant.client.ConditionFactory.matchKeyword;
 import static io.qdrant.client.ValueFactory.value;
 
+import io.qdrant.client.grpc.Common.Filter;
 import java.util.Map;
 
 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
                     .setPayloadAsync(
                         "{collection_name}",

qdrant-landing/content/documentation/headless/snippets/set-payload/by-filter/rust.rs

@@ -3,6 +3,8 @@ use qdrant_client::Payload;
 use serde_json::json;
 
 pub async fn main() -> anyhow::Result<()> {
+    let client = qdrant_client::Qdrant::from_url("http://localhost:6334").build()?; // @hide
+
     client
         .set_payload(
             SetPayloadPointsBuilder::new(

qdrant-landing/content/documentation/headless/snippets/set-payload/by-point-id/go.go

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

qdrant-landing/content/documentation/headless/snippets/set-payload/by-point-id/java.java

@@ -8,6 +8,11 @@ import java.util.Map;
 
 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
                     .setPayloadAsync(
                         "{collection_name}",

qdrant-landing/content/documentation/headless/snippets/set-payload/by-point-id/rust.rs

@@ -1,10 +1,12 @@
 use qdrant_client::qdrant::{
     PointsIdsList, SetPayloadPointsBuilder,
 };
-use qdrant_client::Payload,;
+use qdrant_client::Payload;
 use serde_json::json;
 
 pub async fn main() -> anyhow::Result<()> {
+    let client = qdrant_client::Qdrant::from_url("http://localhost:6334").build()?; // @hide
+
     client
         .set_payload(
             SetPayloadPointsBuilder::new(