[Refactor][OutputProcessor 2/8]: OmniRequestOutput should inherit RequestOutput and no nested wrap-up (#5146)

Signed-off-by: Boao Shi <aoibosh@connect.hku.hk>
Signed-off-by: bowieshi <aoibosh@connect.hku.hk>
Signed-off-by: princepride <wangzhipeng628@gmail.com>
Signed-off-by: R2-Y <ruiruyang2@gmail.com>
Signed-off-by: amy-why-3459 <wuhaiyan17@huawei.com>
Signed-off-by: Shi Boao Bowie <aoibosh@connect.hku.hk>
Co-authored-by: 汪志鹏 <wangzhipeng628@gmail.com>
Co-authored-by: ruirui(rein) yang <73573651+R2-Y@users.noreply.github.com>
Co-authored-by: amy-why-3459 <wuhaiyan17@huawei.com>
Co-authored-by: Gao Han <hgaoaf@connect.ust.hk>
Co-authored-by: Hongsheng Liu <liuhongsheng4@huawei.com>

tests/diffusion/test_diffusion_streaming_output.py

@@ -273,7 +273,7 @@ class TestPipelineStreamingOutputToEntrypoint:
             await _wait_for(lambda: len(pipeline.requests) == 1)
             assert pipeline.requests[0].request_id.startswith("req-omni-")
             assert [output.multimodal_output["metadata"]["stream"]["chunk"] for output in outputs] == [0, 1]
-            assert [getattr(output.request_output, "finished", output.finished) for output in outputs] == [False, True]
+            assert [output.finished for output in outputs] == [False, True]
         finally:
             await self._shutdown_pipeline_omni_harness(omni, fixture, inline_client)