Until Spring Framework 5.1.15, a FactoryBean with a non-default constructor
defined via component scanning would cause an error. This behavior has changed
as of https://github.com/spring-projects/spring-framework/issues/22409.
Regardless of this change we want to ensure that we avoid triggering eager
initialisation. `SimpleFactoryBean` has been written this way so that the tests
fail if early initialization is triggered regardless of the Spring Framework version.
Fixes gh-15898
0c2e71cd08