Refs #34701 -- Moved UniqueConstraint(nulls_distinct) validation tests.

The original tests required the creation of a model that is no longer necessary
and were exercising Model.full_clean(validate_constraints) which has nothing
to do with the nulls_distinct feature.

tests/validation/models.py

@@ -217,17 +217,3 @@ class UniqueConstraintConditionProduct(models.Model):
                 condition=models.Q(color__isnull=True),
             ),
         ]
-
-
-class UniqueConstraintNullsDistinctProduct(models.Model):
-    name = models.CharField(max_length=255, blank=True, null=True)
-
-    class Meta:
-        required_db_features = {"supports_nulls_distinct_unique_constraints"}
-        constraints = [
-            models.UniqueConstraint(
-                fields=["name"],
-                name="name_nulls_not_distinct_uniq",
-                nulls_distinct=False,
-            ),
-        ]