[flagd] shutting down provider should reset the state.

[thiyagu06]

https://github.com/open-feature/java-sdk-contrib/blob/main/providers/flagd/src/main/java/dev/openfeature/contrib/providers/flagd/FlagdProvider.java#L56 It's not always guaranteed that FeatureProvider.shutdown() method is called at the end of application lifecycle. The user can call the shutdown method at any point in time of application lifetime. So it's better to reset the state. may be NOT_READY or new state and publish the event with the new state.