refactor: Unify all json.(loads|dumps) usage to utils.json (#28702)

Co-authored-by: Eyal Ezer <eyal.ezer@ge.com>

tests/unit_tests/db_engine_specs/test_databricks.py

@@ -16,7 +16,6 @@
 # under the License.
 # pylint: disable=unused-argument, import-outside-toplevel, protected-access
 
-import json
 from datetime import datetime
 from typing import Optional
 
@@ -25,6 +24,7 @@ from pytest_mock import MockerFixture
 
 from superset.db_engine_specs.databricks import DatabricksNativeEngineSpec
 from superset.errors import ErrorLevel, SupersetError, SupersetErrorType
+from superset.utils import json
 from tests.unit_tests.db_engine_specs.utils import assert_convert_dttm
 from tests.unit_tests.fixtures.common import dttm  # noqa: F401