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/test_containers_integration_tests/tasks/test_batch_clean_document_task.py

@@ -13,6 +13,7 @@ import pytest
 from faker import Faker
 
 from extensions.ext_database import db
+from libs.datetime_utils import naive_utc_now
 from models.account import Account, Tenant, TenantAccountJoin, TenantAccountRole
 from models.dataset import Dataset, Document, DocumentSegment
 from models.model import UploadFile
@@ -202,7 +203,6 @@ class TestBatchCleanDocumentTask:
             UploadFile: Created upload file instance
         """
         fake = Faker()
-        from datetime import datetime
 
         from models.enums import CreatorUserRole
 
@@ -216,7 +216,7 @@ class TestBatchCleanDocumentTask:
             mime_type="text/plain",
             created_by_role=CreatorUserRole.ACCOUNT,
             created_by=account.id,
-            created_at=datetime.utcnow(),
+            created_at=naive_utc_now(),
             used=False,
         )