refactor(tests): remove magic number and use recursive comparison

- Replace hard-coded hasSize(7) with hasSize(expected.size())
- Replace partial assertions with full recursive comparison
- Improves test robustness in league search test

Author: nanotaboada

src/test/java/ar/com/nanotaboada/java/samples/spring/boot/test/services/PlayersServiceTests.java

@@ -293,8 +293,9 @@ void givenPlayersExist_whenSearchByLeague_thenReturns7Players() {
         // Then
         verify(playersRepositoryMock, times(1)).findByLeagueContainingIgnoreCase(any());
         then(actual)
-                .hasSize(7)
-                .allSatisfy(dto -> then(dto.getLeague()).contains(league));
+                .hasSize(expected.size())
+                .usingRecursiveComparison()
+                .isEqualTo(expected);
     }
 
     /**