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-explore/discovery-basic/go.go

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

qdrant-landing/content/documentation/headless/snippets/query-points-explore/discovery-basic/rust.rs

@@ -1,7 +1,8 @@
 use qdrant_client::qdrant::{ContextInputBuilder, DiscoverInputBuilder, QueryPointsBuilder};
-use qdrant_client::Qdrant;
 
 pub async fn main() -> anyhow::Result<()> {
+    let client = qdrant_client::Qdrant::from_url("http://localhost:6334").build()?; // @hide
+
     client
         .query(
             QueryPointsBuilder::new("{collection_name}").query(