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/insert-points/with-condition/go.go

@@ -12,6 +12,8 @@ func Main() {
 	    Port: 6334,
 	})
 
+	if err != nil { panic(err) } // @hide
+
 	client.Upsert(context.Background(), &qdrant.UpsertPoints{
 	    CollectionName: "{collection_name}",
 	    Points: []*qdrant.PointStruct{

qdrant-landing/content/documentation/headless/snippets/insert-points/with-condition/java.java

@@ -21,7 +21,7 @@ public class Snippet {
                     .upsertAsync(
                         UpsertPoints.newBuilder()
                             .setCollectionName("{collectionName}")
-                            .addPoint(
+                            .addPoints(
                                 PointStruct.newBuilder()
                                     .setId(id(1))
                                     .setVectors(vectors(0.05f, 0.61f, 0.76f, 0.74f))

qdrant-landing/content/documentation/headless/snippets/insert-points/with-condition/typescript.ts

@@ -14,7 +14,7 @@ client.upsert("{collection_name}", {
       },
     }
   ],
-  updateFilter: {
+  update_filter: {
     must: [
       {
         key: "version",