fix: Add Hilla packages always when Hilla is available in classpath

[mshabarov]

Adds Hilla packages always when Hilla is available in classpath, i.e. when not excluded manually.

Fixes #20959
Fixes vaadin/hilla#3211

[sonarqubecloud]

Quality Gate passed

Issues
13 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

Test Results

  929 files   -   236    929 suites   - 236   1h 20m 2s ⏱️ - 16m 32s
5 057 tests  - 2 582  4 998 ✅  - 2 584  56 💤  - 1  2 ❌ +2  1 🔥 +1 
5 288 runs   - 2 646  5 227 ✅  - 2 643  58 💤  - 6  2 ❌ +2  1 🔥 +1 

For more details on these failures and errors, see this check.

Results for commit dc17c21. ± Comparison against base commit feac410.

This pull request removes 2582 tests.

com.vaadin.base.devserver.AbstractDevServerRunnerTest ‑ shouldPassEncodedUrlToDevServer
com.vaadin.base.devserver.AbstractDevServerRunnerTest ‑ updateServerStartupEnvironment_preferIpv4_LocalhostIpAddressAddedToProcessEnvironment
com.vaadin.base.devserver.AbstractDevServerRunnerTest ‑ updateServerStartupEnvironment_preferIpv6_LocalhostIpAddressAddedToProcessEnvironment
com.vaadin.base.devserver.BrowserLiveReloadAccessorImplTest ‑ getLiveReload_devMode_contextHasNoReloadInstance_instanceIsCreated
com.vaadin.base.devserver.BrowserLiveReloadAccessorImplTest ‑ getLiveReload_devMode_contextHasReloadInstance_instanceIsReturned
com.vaadin.base.devserver.BrowserLiveReloadAccessorImplTest ‑ getLiveReload_liveReloadDisabled_instanceIsCreated
com.vaadin.base.devserver.BrowserLiveReloadAccessorImplTest ‑ getLiveReload_productionMode_nullIsReturned
com.vaadin.base.devserver.DebugWindowConnectionTest ‑ backwardsCompatibilityClassExists
com.vaadin.base.devserver.DebugWindowConnectionTest ‑ getBackend_HotSwapVaadinIntegrationClassLoaded_returnsHOTSWAP_AGENT
com.vaadin.base.devserver.DebugWindowConnectionTest ‑ getBackend_JRebelClassEventListenerClassLoaded_returnsJREBEL
…