[Chore/Refactor] Use centralized naive_utc_now for UTC datetime operations (#24352)

Signed-off-by: -LAN- <laipz8200@outlook.com>

api/core/workflow/nodes/llm/llm_utils.py

@@ -1,5 +1,4 @@
 from collections.abc import Sequence
-from datetime import UTC, datetime
 from typing import Optional, cast
 
 from sqlalchemy import select, update
@@ -20,6 +19,7 @@ from core.variables.segments import ArrayAnySegment, ArrayFileSegment, FileSegme
 from core.workflow.entities.variable_pool import VariablePool
 from core.workflow.enums import SystemVariableKey
 from core.workflow.nodes.llm.entities import ModelConfig
+from libs.datetime_utils import naive_utc_now
 from models import db
 from models.model import Conversation
 from models.provider import Provider, ProviderType
@@ -149,7 +149,7 @@ def deduct_llm_quota(tenant_id: str, model_instance: ModelInstance, usage: LLMUs
                 )
                 .values(
                     quota_used=Provider.quota_used + used_quota,
-                    last_used=datetime.now(tz=UTC).replace(tzinfo=None),
+                    last_used=naive_utc_now(),
                 )
             )
             session.execute(stmt)