Drop experimental Lit based versions from V24.9 branch

[web-padawan]

Describe your motivation

We'll have all components based on Lit in V25 and keep using Polymer in V24. It makes no sense to keep Lit versions around especially due to the impact on test duration.

Describe the solution you'd like

Remove vaadin-lit-* entrypoints and generated Lit tests from 24.9 branch. Prototype branch: https://github.com/vaadin/web-components/compare/24.8...chore/drop-lit-versions-24.8

Note

We could consider dropping already from 24.8 but doing that in a patch release is somewhat questionable.