Backports from master to 9.0-stable (#5885)

* MONGOID-5815 Respect client_override for new docs (#5880)

* MONGOID-5805 Short-circuit the logic in extract_attribute to fix performance regression (backport to 8.1-stable) (#5869)

* short-circuit the logic in extract_attribute to fix performance regression

* short circuit on anything that's not a document or hash

* handle hash/string keys

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Co-authored-by: Dmitry Rybakov <[email protected]>

Author: jamis