Stop using getKillStatus to check for OperationContext interruption.

`getKillStatus` captures a subset of the situations under which an OperationContext may be interrupted. It should almost never be used outside of the SA code base.

We provided incorrect guidance for tasks logged under SERVER-56251, and those should be addressed ASAP.

Additionally, a quick look should be done in other places to ensure `getKillStatus` is not being used inappropriately.

This is being done in lieu of SERVER-69496, to avoid changing internal implementation details of OperationContext `kill`.