fix preview and recommend plugins

api/services/rag_pipeline/pipeline_template/remote/remote_retrieval.py

 import requests
 
 from configs import dify_config
+from services.rag_pipeline.pipeline_template.database.database_retrieval import DatabasePipelineTemplateRetrieval
 from services.rag_pipeline.pipeline_template.pipeline_template_base import PipelineTemplateRetrievalBase
 from services.rag_pipeline.pipeline_template.pipeline_template_type import PipelineTemplateType
 from services.recommend_app.buildin.buildin_retrieval import BuildInRecommendAppRetrieval
         try:
             result = self.fetch_pipeline_template_detail_from_dify_official(template_id)
         except Exception as e:
-            logger.warning("fetch recommended app detail from dify official failed: %r, switch to built-in.", e)
-            result = BuildInRecommendAppRetrieval.fetch_recommended_app_detail_from_builtin(template_id)
+            logger.warning("fetch recommended app detail from dify official failed: %r, switch to database.", e)
+            result = [DatabasePipelineTemplateRetrieval.fetch_pipeline_template_detail_from_db(template_id)]
         return result
 
     def get_pipeline_templates(self, language: str) -> dict:
         try:
             result = self.fetch_pipeline_templates_from_dify_official(language)
         except Exception as e:
-            logger.warning("fetch pipeline templates from dify official failed: %r, switch to built-in.", e)
-            result = BuildInRecommendAppRetrieval.fetch_recommended_apps_from_builtin(language)
+            logger.warning("fetch pipeline templates from dify official failed: %r, switch to database.", e)
+            result = DatabasePipelineTemplateRetrieval.fetch_pipeline_templates_from_db(language)
         return result
 
     def get_type(self) -> str: