Drop deprecated class aliases with Element suffix

[web-padawan]

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Motivation

As part of #1993 we added legacy class aliases to the vaadin- prefixed packages, e.g.

import { GridElement } from '@vaadin/vaadin-grid';

In Vaadin 22 these already come as deprecated (VS Code users see the warning when importing). Also the TS components examples in docs already use new classes GridElement -> Grid.

Proposed solution

Remove legacy class aliases with Element suffix in Vaadin 23 first alpha.

[web-padawan]

As discussed internally, we shouldn't remove things immediately but a console warning needs to be shown first.

[web-padawan]

Done in #4844.