fix LoggerConfig inconsistency bug

[mski-iksm]

gokart.build() has a feature to disable low important logs. However, the implementation has inconsistency,

• logging.disable(self.level): disable any logs with level same or below the self.level
• self.logger.setLevel(self.level): enable any logs same or above the self.level

This is because logging.Logger.setLevel and logging.disable has the following difference.

setLevel: Logging messages which are less severe than level will be ignored logging.disable: disable all logging calls of severity level and below

This PR fix the inconsistency by disabling any logs with level below the self.level

[hirosassa]

Thanks! LGTM