NC | Update config might result with deleted config file

[romayalon]

Environment info

• NooBaa Version: 4.19
• Platform: NC

Actual behavior

1. While debugging notifications + lifecycle, in an old version of NC lifecycle we used update_config_file() and we saw that on some failure the buckets config files were deleted, therefore we checked the code and saw that
   it might be because of the next line -

await safe_unlink(fs_context, config_path, stat, undefined, tmp_dir_path); 

we need to evaluate this code more and fix this potential issue.

Expected behavior

1. config files can not be deleted as a result of a failure of update_config_file()

Steps to reproduce

1. it's probably can be reproducible artificially when throwing an error after the safe_unlink()

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