fix(api): Fix resetting sys var causing internal server error (#21604)

and sorts draft variables by their creation time, ensures a consist order.

api/core/workflow/repositories/draft_variable_repository.py

@@ -0,0 +1,32 @@
+import abc
+from collections.abc import Mapping
+from typing import Any, Protocol
+
+from sqlalchemy.orm import Session
+
+from core.workflow.nodes.enums import NodeType
+
+
+class DraftVariableSaver(Protocol):
+    @abc.abstractmethod
+    def save(self, process_data: Mapping[str, Any] | None, outputs: Mapping[str, Any] | None):
+        pass
+
+
+class DraftVariableSaverFactory(Protocol):
+    @abc.abstractmethod
+    def __call__(
+        self,
+        session: Session,
+        app_id: str,
+        node_id: str,
+        node_type: NodeType,
+        node_execution_id: str,
+        enclosing_node_id: str | None = None,
+    ) -> "DraftVariableSaver":
+        pass
+
+
+class NoopDraftVariableSaver(DraftVariableSaver):
+    def save(self, process_data: Mapping[str, Any] | None, outputs: Mapping[str, Any] | None):
+        pass