text: Title: catplot with redundant hue assignment creates empty legend with title
  Body: ```python
  sns.catplot(tips, x="day", y="total_bill", hue="day", col="sex", row="smoker", kind="box", height=3)
  ```
  ![image](https://github.com/mwaskom/seaborn/assets/315810/53b0af1e-e133-46bb-92bd-78c91db0221b)
  
  Set `legend=False` to workaround, but with default `legend='auto'` this should be disabled due to the redundancy.