incorrect annotation on AbstractLoginModule

AbstractLoginModule is incorrectly annotated with @ProviderType [1] as the documentation in [0] describes the class as the basic extension point for authentication and even provides an example. This is causing a backwards compatibility issue in an upstream product due to code quality scans.

[0] https://jackrabbit.apache.org/oak/docs/security/authentication.html

[1]https://jackrabbit.apache.org/oak/docs/apidocs/org/apache/jackrabbit/oak/spi/security/authentication/AbstractLoginModule.html