feat(core): make openai and mlx embedding progress bars conditional on build mode

[pritpatel2412]

Summary

This PR addresses two existing TODO: @yichuan-w add progress bar only in build mode comments inside embedding_compute.py.

Changes Made

• Added the is_build parameter to compute_embeddings_openai and compute_embeddings_mlx.
• Threaded is_build down from the main compute_embeddings dispatcher.
• Conditionally instantiate the tqdm progress bar iterator only when is_build=True for both OpenAI and MLX providers, preventing unnecessary log spam during non-build usage.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature / Enhancement (non-breaking change which adds functionality/cleans up logs)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

[ASuresh0524]

@pritpatel2412 this pr looks good, could we fix linting so I can merge, thanks for contribution!

[pritpatel2412]

Done Please check it