Fix Hilla stats to detect Lit vs. React usage based on deployment configuration

[taefi]

Describe the bug

Hilla stats where being gathered based on the usage of hilla-react artifact, and now that the hilla-react is not there anymore, we can decide whether is it a Lit or React app based on DeplymentConfiguration's method called isReactEnabled.

Expected-behavior

• The statistics should be gathered once per application startup.
• It would be ideal if the statistics gathered based on real usages of Hilla, not just Hilla artifacts being present on classpath, as in Vaadin 24.4+, Hilla is automatically part of the platform, unless it is excluded explicitely.

Reproduction

Previous unit test for HillaStats is failing.

System Info

N/A