Check for interrupt before initializing the _tenantOplogApplier

_interrupt calls _cancelRemainingWork which would cancel the _tenantOplogApplier if it exists. But I think it is possible for the _tenantOplogApplier to be initialized after _cancelRemainingWork is called. In that case, the _tenantOplogApplier would never be shut down. I think we should check for interrupt before initializing the _tenantOplogApplier.