fixing mm placeholder replacement issue with gemma3 (#27538)

Signed-off-by: tingtingtang1992 <[email protected]>

Author: tingtingtang1992

vllm/model_executor/models/gemma3_mm.py

@@ -403,7 +403,7 @@ def _find_mm_placeholders(
 
         def get_repl_toks(tok: int) -> list[int]:
             if tok == newline_3:
-                return [newline_1, newline_2]
+                return [newline_2, newline_1]
             if tok == newline_4:
                 return [newline_2, newline_2]