[Architecture] Refactor models to remove @Self references when no longer needed

To ensure that this library's models are safe to be `cache=true`, the model implementations should be modified to remove all references to `@Self` at the end of the constructors/`@PostConstruct` methods.

See [the Sling Models docs](https://sling.apache.org/documentation/bundles/models.html#a-note-about-cache-true-and-using-the-self-injector) for an explanation.

Start by reading the linked Sling Models documentation, especially the note about cache=true and the Self injector. Review the library's model implementations and their constructors or @PostConstruct methods, then verify that no unnecessary @Self references remain at the end of those methods.

Written by the indexing model from the issue text.