[Validator] re-added support for 2.4 API version in tests

Author: fabpot

Tests/Constraints/AbstractConstraintValidatorTest.php

@@ -113,6 +113,7 @@ protected function createContext()
                     $translator
                 );
                 break;
+            case Validation::API_VERSION_2_4:
             case Validation::API_VERSION_2_5_BC:
                 $context = new LegacyExecutionContext(
                     $validator,