Fixed some tests

.gitlab-ci.yml

...rvice/src/main/java/at/tuwien/endpoints/UserEndpoint.java

...c/test/java/at/tuwien/endpoints/UserEndpointUnitTest.java

...test/java/at/tuwien/gateway/BrokerServiceGatewayTest.java

...ava/at/tuwien/service/DatabaseServiceIntegrationTest.java

...at/tuwien/service/MessageQueueServiceIntegrationTest.java

...src/main/java/at/tuwien/gateway/BrokerServiceGateway.java

...java/at/tuwien/gateway/impl/BrokerServiceGatewayImpl.java

.../src/main/java/at/tuwien/service/MessageQueueService.java

...main/java/at/tuwien/service/impl/RabbitMqServiceImpl.java