rm extra print statements & replace create tmpfile function

[nightosong]

Description

1. _get_candidate_names function is an internal implementation detail of the tempfile module and mkstemp is a better choice.
2. in the branch where key is empty, there are unnecessary and redundant print statements that need to be removed.

Fixes # (issue)

Version Bump?

Did I bump the version in the pyproject.toml file of the package I am updating? (Except for the llama-index-core package)

• Yes

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• I stared at the code and made sure it makes sense

Suggested Checklist:

• I have performed a self-review of my own code
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes