Delay Calculation for INSERTs Updated to Use Proportional Formula

Delay for INSERT can be calculated incorrectly, which can lead to always using max_delay_to_insert setting as delay instead of a correct value. Using simple formula max_delay_to_insert * (parts_over_threshold/max_allowed_parts_over_threshold) i.e. delay grows proportionally to parts over threshold. Closes #44902. #44954 (Igor Nikonov).