AbstractComponentRegistry.getComponent can return an incomplete component

AbstractComponentRegistry.getComponent doesn't have any locking, so it's possible for a thread to retrieve a component while another thread is injecting that component's dependencies.

Normally this isn't a problem, because the global registry is locked during cache manager startup, and the cache registry is locked during cache startup. However, some global components are only created "on-demand", because a cache component depends on them, and this can happen if someone uses getComponent instead of getOrCreateComponent.