fix embed stage ignoring pipeline endpoint

[edknv]

Description

Fixes an error in the main nv-ingest pipeline:

No embedding endpoint configured (endpoint_url/embedding_nim_endpoint are empty) and no local embedder was provided in task_config['embedder']

• Revert config lookups in embed_text.py that was introduced in Retriever #1427 to previoius state.
• Flip if/elif priority to prefer local embedder over remote endpoint, removing the need to null out the endpoint to use a local embedder

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.
• If adjusting docker-compose.yaml environment variables have you ensured those are mimicked in the Helm values.yaml file.