feat!: complete deprecation and cleanup of multimodal blob APIs

packages/bigframes/bigframes/bigquery/_operations/ai.py

@@ -1201,9 +1201,6 @@ def _separate_context_and_series(
         return [None], [series.Series([prompt])]
 
     if isinstance(prompt, series.Series):
-        if prompt.dtype == dtypes.OBJ_REF_DTYPE:
-            # Multi-model support
-            return [None], [prompt.blob.read_url()]
         return [None], [prompt]
 
     prompt_context: List[str | None] = []
@@ -1238,9 +1235,6 @@ def _convert_series(
 ) -> series.Series:
     result = convert.to_bf_series(s, default_index=None, session=session)
 
-    if result.dtype == dtypes.OBJ_REF_DTYPE:
-        # Support multimodel
-        return result.blob.read_url()
     return result