Integration tests are broken (because using @Inject)

[clementguillot]

Description

Almost all our integration tests are broken. Just run ./gradlew :apps:server:testNative to observe.

This is due to usage of @Inject properties in test classes, as documented here:

It is also possible to test native executables using @QuarkusIntegrationTest. This supports all the features mentioned in this guide except injecting into tests (and the native executable runs in a separate non-JVM process this is not really possible).

So, we need to refactor our tests, to no longer rely on injected fields, and use HTTP endpoints or CLI commands instead.