Image validation of the image2text model without using local paths (#9052)

### What problem does this PR solve?

#9050

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

api/apps/llm_app.py

@@ -15,7 +15,7 @@
 #
 import logging
 import json
-import os
+import base64
 from flask import request
 from flask_login import login_required, current_user
 from api.db.services.llm_service import LLMFactoriesService, TenantLLMService, LLMService
@@ -24,7 +24,7 @@ from api.utils.api_utils import server_error_response, get_data_error_result, va
 from api.db import StatusEnum, LLMType
 from api.db.db_models import TenantLLM
 from api.utils.api_utils import get_json_result
-from api.utils.file_utils import get_project_base_directory
+from api.utils.base64_image import test_image_base64
 from rag.llm import EmbeddingModel, ChatModel, RerankModel, CvModel, TTSModel
 
 
@@ -256,8 +256,8 @@ def add_llm():
             base_url=llm["api_base"]
         )
         try:
-            with open(os.path.join(get_project_base_directory(), "web/src/assets/yay.jpg"), "rb") as f:
-                m, tc = mdl.describe(f.read())
+            image_data = base64.b64decode(test_image_base64)
+            m, tc = mdl.describe(image_data)
             if not m and not tc:
                 raise Exception(m)
         except Exception as e: