Fix the range definition and remove the --use-discrete-uniform option from OptunaSolverFactory

[HideakiImamura]

Optuna v3.0 has been released, and it deprecated the old suggest APIs. We should use the stable suggest APIs.

What we should change

• We should use suggest_float, suggest_int, and suggest_categorical here.
• To fix above, we need to fix the range definition here. Concretely, for example, we should add FloatRange and IntRange to represent the range for suggest_float and suggest_int respectively.
• Thanks to above fix, we can remove --use-discrete-uniform option from OptunaSolverFactory. We can also fix the kurobako here.