fix: Always wait a small amount of time between inserts (#3168)

* Always wait a small amount of time between inserts

* Ruff 🐶

* Parametrize sleep and sleep on empty queue

* Ruff 🐶

* Await sleep

* Update src/phoenix/db/bulk_inserter.py

Co-authored-by: Roger Yang <80478925+RogerHYang@users.noreply.github.com>

* fix: unflatten attributes when loading spans from `trace_dataset` (#3170)

* chore(main): release arize-phoenix 4.0.2 (#3152)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

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Co-authored-by: Roger Yang <80478925+RogerHYang@users.noreply.github.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>