Fix NEGATING_SIMPLE_PROPERTY to use IS NOT NULL when argument is null

When a query method uses NEGATING_SIMPLE_PROPERTY and the argument is null,
the generated query should now use `IS NOT NULL` instead of `<>`. This ensures
consistent behavior when handling null values across queries.

Changes:
- Updated `JpaQueryCreator` to handle null arguments in `NEGATING_SIMPLE_PROPERTY` by rewriting `<>` to `IS NOT NULL`.

Closes spring-projects#3675

Author: bezzang-dev

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryCreator.java

@@ -311,8 +311,10 @@ public Predicate build() {
 					return expression.isIsNullParameter() ? path.isNull()
 							: builder.equal(upperIfIgnoreCase(path), upperIfIgnoreCase(expression.getExpression()));
 				case NEGATING_SIMPLE_PROPERTY:
-					return builder.notEqual(upperIfIgnoreCase(getTypedPath(root, part)),
-							upperIfIgnoreCase(provider.next(part).getExpression()));
+					ParameterMetadata<Object> negatedExpression = provider.next(part);
+					Expression<Object> negatedPath = getTypedPath(root, part);
+					return negatedExpression.isIsNullParameter() ? negatedPath.isNotNull()
+							: builder.notEqual(upperIfIgnoreCase(negatedPath), upperIfIgnoreCase(negatedExpression.getExpression()));
 				case IS_EMPTY:
 				case IS_NOT_EMPTY: