OZG-6239 Cleanup model annotations

src/main/java/de/ozgcloud/xta/test/app/config/XTAServer.java

src/main/java/de/ozgcloud/xta/test/app/model/XtaFile.java

.../ozgcloud/xta/test/app/model/XtaLookupServiceRequest.java

...va/de/ozgcloud/xta/test/app/model/XtaMessageMetaData.java

...zgcloud/xta/test/app/model/XtaMessageMetaDataListing.java

.../xta/test/app/model/XtaMessageMetaDataListingRequest.java

...zgcloud/xta/test/app/validation/RequestValidatorTest.java