HHH-8923 - Reconsider closing of ServiceRegistry instances

Conflicts:
	hibernate-core/src/main/java/org/hibernate/boot/registry/BootstrapServiceRegistryBuilder.java
	hibernate-core/src/main/java/org/hibernate/boot/registry/StandardServiceRegistryBuilder.java
	hibernate-core/src/main/java/org/hibernate/boot/registry/internal/BootstrapServiceRegistryImpl.java
	hibernate-core/src/main/java/org/hibernate/boot/registry/internal/StandardServiceRegistryImpl.java
	hibernate-core/src/main/java/org/hibernate/service/internal/AbstractServiceRegistryImpl.java
	hibernate-core/src/test/java/org/hibernate/connection/ConnectionCreatorTest.java