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/query-points/random-sample/go.go

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

qdrant-landing/content/documentation/headless/snippets/query-points/random-sample/python.py

@@ -1,5 +1,6 @@
 from qdrant_client import QdrantClient, models
 
+client = QdrantClient(url="http://localhost:6333")
 
 sampled = client.query_points(
     collection_name="{collection_name}",

qdrant-landing/content/documentation/headless/snippets/query-points/random-sample/rust.rs

@@ -1,5 +1,5 @@
 use qdrant_client::Qdrant;
-use qdrant_client::qdrant::{Query, QueryPointsBuilder};
+use qdrant_client::qdrant::{Query, QueryPointsBuilder, Sample};
 
 pub async fn main() -> anyhow::Result<()> {
     let client = Qdrant::from_url("http://localhost:6334").build()?;
@@ -11,5 +11,6 @@ pub async fn main() -> anyhow::Result<()> {
         )
         .await?;
 
+    _ = sampled; // @hide
     Ok(())
 }