Add check for Prescaler-buffered prescale

Fix should solve one of the cases when AutoPrescaler is not reverting to the original prescale ATR-27286

It was observed when a prescale from RuleChecker was buffered in Prescaler, but between the Prescaler buffer checks the spike finished, and the original prescale could be used. The initially sent prescale acting on the spike was not being overwritten in Prescaler.

The buffering mechanism introduced in the MenuDraft validation is described in the diagram below:

The fix was tested at P1 https://atlasop.cern.ch/elisa/display/519561

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