fix(vlm): handle legacy conversation data format and check image in data (#2018) [skip ci]

* fix: handle legacy conversation data format and check image in data

* feat: add test for llama vision

* feat: add max_steps to test

* fix: incorrect indent and return preprocess

* feat: use smaller model and dataset

* chore: add extra config for sharegpt dataset

tests/e2e/test_lora_llama.py

@@ -57,6 +57,7 @@ class TestLoraLlama(unittest.TestCase):
                 "learning_rate": 0.00001,
                 "optimizer": "adamw_torch",
                 "lr_scheduler": "cosine",
+                "max_steps": 20,
             }
         )
         normalize_config(cfg)