[BUG] fix: release orphaned data handle after auto-format in load_data_source

[KaranSinghDev]

What does this implement/fix? Explain your changes.

When load_data_source runs with auto-format enabled (the default), it creates a raw data handle, then calls format_data_handle() which creates a second formatted handle. Only the formatted handle is returned to the caller, but the raw intermediate handle was never deleted from _data_handles. This caused the internal dict to grow by 2 per call instead of 1, with no cap or eviction on data handles.

Does your contribution introduce a new dependency? If yes, which one?

No

What should a reviewer concentrate their feedback on?

1. executor.py — the two del self._data_handles[data_handle] lines, one in each code path
2. Confirm the fallback path (where auto-format fails) is untouched and still returns the raw handle correctly

Any other comments?

I removed the original_handle from the sync response, it pointed to the deleted handle and would cause a "handle not found" error if used.

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