flush before updating legacy-ids

src/test/java/net/hostsharing/hsadminng/hs/office/migration/ImportOfficeData.java

@@ -596,6 +596,7 @@ public class ImportOfficeData extends ContextBasedTest {
             Map<Integer, E> entities,
             final String legacyIdTable,
             final String legacyIdColumn) {
+        em.flush();
         entities.forEach((id, entity) -> em.createNativeQuery("""
                             UPDATE ${legacyIdTable}
                                 SET ${legacyIdColumn} = :legacyId