Model selection setting doesnt appear in the interactive settings dialog

There is a setting that allows a user to persist what model they want to use, but its not shown because of a bug in its setting. This causes users to have to re-select their model of choice every time they start a session

issue: https://github.com/google-gemini/gemini-cli/issues/17987

fix: https://github.com/google-gemini/gemini-cli/pull/17989