Refa: update gemini2.5 (#7822)

### What problem does this PR solve?

Update gemini2.5

### Type of change

- [x] Refactoring

conf/llm_factories.json

             "status": "1",
             "llm": [
                 {
-                    "llm_name": "gemini-2.5-flash-preview-04-17",
+                    "llm_name": "gemini-2.5-flash-preview-05-20",
                     "tags": "LLM,CHAT,1024K,IMAGE2TEXT",
                     "max_tokens": 1048576,
                     "model_type": "image2text",
                     "model_type": "image2text"
                 },
                 {
-                    "llm_name": "gemini-2.5-pro-exp-03-25",
+                    "llm_name": "gemini-2.5-pro-preview-05-06",
                     "tags": "LLM,IMAGE2TEXT,1024K",
                     "max_tokens": 1048576,
                     "model_type": "image2text"