Update dataframe.py (#28871)

community: optimize DataFrame document loader

**Description:**
Simplify the `lazy_load` method in the DataFrame document loader by
combining text extraction and metadata cleanup into a single operation.
This makes the code more concise while maintaining the same
functionality.

**Issue:** N/A

**Dependencies:** None

**Twitter handle:** N/A

libs/community/langchain_community/document_loaders/dataframe.py

@@ -21,9 +21,8 @@ def lazy_load(self) -> Iterator[Document]:
         """Lazy load records from dataframe."""
 
         for _, row in self.data_frame.iterrows():
-            text = row[self.page_content_column]
             metadata = row.to_dict()
-            metadata.pop(self.page_content_column)
+            text = metadata.pop(self.page_content_column)
             yield Document(page_content=text, metadata=metadata)