Retain return type from @dispatcher.span (#17817)

...ore/llama_index/core/chat_engine/condense_plus_context.py

...x-core/llama_index/core/evaluation/retrieval/evaluator.py

...x-core/llama_index/core/extractors/metadata_extractors.py

...a-index-core/llama_index/core/indices/common_tree/base.py

...index-core/llama_index/core/instrumentation/dispatcher.py

llama-index-core/llama_index/core/llms/llm.py

llama-index-core/llama_index/core/output_parsers/pydantic.py

...a-index-core/llama_index/core/program/function_program.py

llama-index-core/llama_index/core/program/llm_program.py

llama-index-core/llama_index/core/program/utils.py

...lama_index/core/query_engine/retry_source_query_engine.py

...re/llama_index/core/query_engine/sql_join_query_engine.py

llama-index-core/llama_index/core/query_pipeline/query.py

.../llama_index/core/response_synthesizers/tree_summarize.py

llama-index-core/llama_index/core/tools/retriever_tool.py

llama-index-core/llama_index/core/types.py

...ode_parser/llama-index-node-parser-docling/pyproject.toml

...dex-node-parser-docling/tests/test_node_parser_docling.py