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/collection-aliases/switch/go.go

@@ -1,8 +1,17 @@
 package snippet
 
 import "context"
+import "github.com/qdrant/go-client/qdrant" // @hide
 
 func Main() {
+	// @hide-start
+	client, err := qdrant.NewClient(&qdrant.Config{
+	    Host: "localhost",
+	    Port: 6334,
+	})
+	if err != nil { panic(err) }
+	// @hide-end
+
 	client.DeleteAlias(context.Background(), "production_collection")
 	client.CreateAlias(context.Background(), "production_collection", "example_collection")
 }