Try to stepdown before shutting down, even when using 'force'

Currently if you specify

to the shutdown command, we completely skip the step of trying to wait for a secondary to catch up and step down before shutting down the primary. Instead we should block writes and try to wait for a secondary to catch up, but then proceed anyway even if no secondary does actually catch up in time. This will match the behavior of stepdown which was changed in 2.8 to behave like this already.