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/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}",