Remove client sink class from stream stub

Summary:
- Client sink class was incorrectly added in stream interfaces but never used
 - When Sink support was added, it is correctly added in sink.pyi
 - Remove it from stream for cleanup

Reviewed By: Sunnie912

Differential Revision: D83259863

fbshipit-source-id: 2fe8849114a73ae53f48796ed94b369f62a30195

Author: Vishwa Prakash Gayasen

third-party/thrift/src/thrift/lib/python/streaming/stream.pyi

@@ -14,17 +14,11 @@
 
 # pyre-strict
 
-from typing import AsyncIterator, Generic, TypeVar
+from typing import AsyncIterator, TypeVar
 
 TChunk = TypeVar("TChunk")
 TFinalResponse = TypeVar("TFinalResponse")
 
-class ClientSink(Generic[TFinalResponse]):
-    def __init__(self) -> None: ...
-    async def sink(
-        self, iterator: AsyncIterator[TChunk]
-    ) -> Generic[TFinalResponse]: ...
-
 class ClientBufferedStream(AsyncIterator[TChunk]):
     def __aiter__(self) -> AsyncIterator[TChunk]: ...
     async def __anext__(self) -> TChunk: ...