Log level not updated when not specified

Overview

In gitlab-com/gl-infra/production#17848 (closed) an engineer had to debug something in production, so they enabled debug logging. However when we removed log_level gitlab-runner didn't update the log level to be info (default), and stayed in debug mode filling up the disk.

1. Start GitLab Runner process with log_level not specified.
2. Update config.toml to specify log_level = "debug".
3. Wait for GitLab Runner to reload config
4. Delete log_level = "debug".
5. Want: Log level to drop to info again (default)
6. Got: Log level stayed as debug

Screen_Recording_2024-04-17_at_11.41.14