[3.12] gh-102024: Reduced _idle_semaphore.release calls (GH-102025) (#104959)

gh-102024: Reduced _idle_semaphore.release calls (GH-102025)

Reduced _idle_semaphore.release calls in concurrent.futures.thread._worker
_idle_semaphore.release() is now only called if only work_queue is empty.

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(cherry picked from commit 0242e9a57aa87ed0b5cac526f65631c654a39054)

Co-authored-by: Andrii Kuzmin <jack.cvr@gmail.com>
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>