Remove DisposableBeanMethodInterceptor

Previously, any @Configuration class was enhanced to namely implement
DisposableBean in order to remove static callbacks that were registered
for that class. This leads to problem if an ApplicationContext is created
and destroyed within the lifecycle on another ApplicationContext in the
same class loader.

It turns out that the destruction callback is no longer necessary as the
interceptors are now stateless: the VM is free to reclaim any of those if
necessary.

Issue: SPR-12445