replace mock object by lombok in BuildConfigurationTest class

Signed-off-by: Oleksandr Krutko <alexander.krutko@gmail.com>

jkube-kit/config/image/src/test/java/org/eclipse/jkube/kit/config/image/build/BuildConfigurationTest.java

@@ -189,12 +189,10 @@ void cacheFrom() {
 
   @Test
   void testBuilder() {
-    AssemblyConfiguration mockAssemblyConfiguration = mock(AssemblyConfiguration.class);
     // Given
-    when(mockAssemblyConfiguration.getName()).thenReturn("1337");
     // When
     final BuildConfiguration result = BuildConfiguration.builder()
-        .assembly(mockAssemblyConfiguration)
+        .assembly(AssemblyConfiguration.builder().name("1337").build())
         .user("super-user")
         .build();
     // Then