fix: drop dead code phase2 unused class (#22042)

Signed-off-by: yihong0618 <zouzou0208@gmail.com>

api/core/rag/extractor/blob/blob.py

@@ -9,8 +9,7 @@ from __future__ import annotations
 
 import contextlib
 import mimetypes
-from abc import ABC, abstractmethod
-from collections.abc import Generator, Iterable, Mapping
+from collections.abc import Generator, Mapping
 from io import BufferedReader, BytesIO
 from pathlib import Path, PurePath
 from typing import Any, Optional, Union
@@ -143,21 +142,3 @@ class Blob(BaseModel):
         if self.source:
             str_repr += f" {self.source}"
         return str_repr
-
-
-class BlobLoader(ABC):
-    """Abstract interface for blob loaders implementation.
-
-    Implementer should be able to load raw content from a datasource system according
-    to some criteria and return the raw content lazily as a stream of blobs.
-    """
-
-    @abstractmethod
-    def yield_blobs(
-        self,
-    ) -> Iterable[Blob]:
-        """A lazy loader for raw data represented by Blob object.
-
-        Returns:
-            A generator over blobs
-        """