Fix: correct regex for file-preview URL re-signing (#25620)

Fixes #25619

The regex patterns for file-preview and image-preview contained an unescaped `?`, 
which caused incorrect matches such as `file-previe` or `image-previw`. 
This led to malformed URLs being incorrectly re-signed.

Changes:
- Escape `?` in both file-preview and image-preview regex patterns.
- Ensure only valid URLs are re-signed.

Added unit tests to cover:
- Valid file-preview and image-preview URLs (correctly re-signed).
- Misspelled file/image preview URLs (no longer incorrectly matched).

Other:
- Fix a deprecated function `datetime.utcnow()`

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Asuka Minato <i@asukaminato.eu.org>
Co-authored-by: crazywoola <100913391+crazywoola@users.noreply.github.com>

api/tests/unit_tests/core/repositories/test_workflow_node_execution_conflict_handling.py

@@ -1,6 +1,5 @@
 """Unit tests for workflow node execution conflict handling."""
 
-from datetime import datetime
 from unittest.mock import MagicMock, Mock
 
 import psycopg2.errors
@@ -16,6 +15,7 @@ from core.workflow.entities.workflow_node_execution import (
     WorkflowNodeExecutionStatus,
 )
 from core.workflow.enums import NodeType
+from libs.datetime_utils import naive_utc_now
 from models import Account, WorkflowNodeExecutionTriggeredFrom
 
 
@@ -74,7 +74,7 @@ class TestWorkflowNodeExecutionConflictHandling:
             title="Test Node",
             index=1,
             status=WorkflowNodeExecutionStatus.RUNNING,
-            created_at=datetime.utcnow(),
+            created_at=naive_utc_now(),
         )
 
         original_id = execution.id
@@ -112,7 +112,7 @@ class TestWorkflowNodeExecutionConflictHandling:
             title="Test Node",
             index=1,
             status=WorkflowNodeExecutionStatus.SUCCEEDED,
-            created_at=datetime.utcnow(),
+            created_at=naive_utc_now(),
         )
 
         # Save should update existing record
@@ -157,7 +157,7 @@ class TestWorkflowNodeExecutionConflictHandling:
             title="Test Node",
             index=1,
             status=WorkflowNodeExecutionStatus.RUNNING,
-            created_at=datetime.utcnow(),
+            created_at=naive_utc_now(),
         )
 
         # Save should raise IntegrityError after max retries
@@ -199,7 +199,7 @@ class TestWorkflowNodeExecutionConflictHandling:
             title="Test Node",
             index=1,
             status=WorkflowNodeExecutionStatus.RUNNING,
-            created_at=datetime.utcnow(),
+            created_at=naive_utc_now(),
         )
 
         # Save should raise error immediately