feat(config): Add @ConditionalOnMissingBean annotation to service beans in configuration classes

src/main/java/de/extio/game_engine/event/EventsAutoConfiguration.java

@@ -1,6 +1,7 @@
 package de.extio.game_engine.event;
 
 import org.springframework.boot.autoconfigure.AutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.context.annotation.Bean;
 
@@ -19,6 +20,7 @@ public class EventsAutoConfiguration {
 	}
 
 	@Bean
+	@ConditionalOnMissingBean
 	EventService eventService(final EventHandlerRegistry registry, final EventExecutor executor) {
 		final EventService eventService = new EventServiceImpl(registry, executor);
 		return eventService;