fix: Update vector-search samples (Article 1)

[diberry]

Description

This PR updates the vector-search samples (Article 1) to standardize collection lifecycle management across all 5 languages (Python, TypeScript, Go, Java, .NET).

Changes

• Standardizes collection drop behavior: drop at start (if exists), always drop at end
• Improves sample reliability and consistency
• Matches the pattern used in select-algorithm samples (Article 2/3)

Context

These changes were originally bundled in PR #74 (Article 2/3 select-algorithm samples) but have been extracted into this separate PR as they pertain to Article 1 vector-search samples.

Files Changed

Go:

• ai/vector-search-go/src/create_embeddings.go
• ai/vector-search-go/src/diskann.go
• ai/vector-search-go/src/hnsw.go
• ai/vector-search-go/src/ivf.go
• ai/vector-search-go/src/show_indexes.go

Java:

• ai/vector-search-java/src/main/java/com/azure/documentdb/samples/DiskAnn.java
• ai/vector-search-java/src/main/java/com/azure/documentdb/samples/HNSW.java
• ai/vector-search-java/src/main/java/com/azure/documentdb/samples/IVF.java

Python:

• ai/vector-search-python/src/diskann.py
• ai/vector-search-python/src/hnsw.py
• ai/vector-search-python/src/ivf.py

TypeScript:

• ai/vector-search-typescript/src/diskann.ts
• ai/vector-search-typescript/src/hnsw.ts
• ai/vector-search-typescript/src/ivf.ts

.NET:

• ai/vector-search-dotnet/Services/VectorSearchService.cs

[diberry]

ℹ️ These vector-search sample updates were extracted from PR #74 (Article 2/3 select-algorithm samples) to keep concerns separated. PR #74 now contains only Article 2/3 code.