When we're destroying a `PDFPageProxy`-instance, during full document destruction, we'll force-abort any worker-thread parsing of operatorLists. Hence we should make sure that any pending cancel timeout is always aborted, since a later `PDFPageProxy._abortOperatorList` call should always "replace" a previous one.
*Please note:* Technically this was always wrong, but with the changes in PR 15825 it became *ever so slightly* easier to trigger this thanks to the potentially longer timeout.