added DB cleanup to UserControllerTest.java

Author: sergeycherkasovv

src/test/java/hexlet/code/controller/api/UserControllerTest.java

@@ -65,6 +65,8 @@ class UserControllerTest {
 
     @BeforeEach
     void setUp() {
+        userRepository.deleteAll();
+
         mvc = MockMvcBuilders.webAppContextSetup(wac)
                 .defaultResponseCharacterEncoding(StandardCharsets.UTF_8)
                 .apply(springSecurity())