Update partition_router validation for asynx retriever

Author: lazebnyi

airbyte_cdk/sources/declarative/parsers/model_to_component_factory.py

@@ -1900,6 +1900,8 @@ def _merge_stream_slicers(
     ) -> Optional[StreamSlicer]:
         retriever_model = model.retriever
 
+        stream_slicer = self._build_stream_slicer_from_partition_router(retriever_model, config)
+
         if retriever_model.type == "AsyncRetriever":
             is_not_datetime_cursor = (
                 model.incremental_sync.type != "DatetimeBasedCursor"
@@ -1919,13 +1921,11 @@ def _merge_stream_slicers(
                     "AsyncRetriever with cursor other than DatetimeBasedCursor is not supported yet."
                 )
 
-            if is_partition_router:
+            if is_partition_router and not stream_slicer:
                 # Note that this development is also done in parallel to the per partition development which once merged
                 # we could support here by calling create_concurrent_cursor_from_perpartition_cursor
                 raise ValueError("Per partition state is not supported yet for AsyncRetriever.")
 
-        stream_slicer = self._build_stream_slicer_from_partition_router(retriever_model, config)
-
         if model.incremental_sync:
             return self._build_incremental_cursor(model, stream_slicer, config)