refactor(element): use swiper state for init/destroy tracking

[eduardobattisti]

If approved, this PR:

• Uses swiper state to define the initialization/destroy behavior. Using the state defined in the web component was not reflected, because the initialize and destroy methods only update the swiper instance state.

In the case of disconnectedCallback. Only will it be triggered if the component is removed from the DOM.

Fixes: #7666

[eduardobattisti]

I noticed that most of the codebase does not use optional chaining, so I presumed that it is a coding standard. If necessary, I can update this code to use it.