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/inference/query/rust.rs

@@ -1,5 +1,5 @@
 use qdrant_client::{
-    Qdrant, QdrantError,
+    Qdrant,
     qdrant::{Document, Query, QueryPointsBuilder},
 };