Local Docker test script: switch parameter to always delete/recreate container before copying

[DTW-DanWard]

Rather than re-copying over preexisting content on a container, delete the container and recreate each time if user passes switch param.

If performance tests are good, rather than specifying param, could make delete/recreate the default. Downside is if user is also connected to container (manually poking about, running tests, etc.), stopping and deleting container might not be a wise.... could prompt user...?

[DTW-DanWard]

Also, delete container before attempting to copy rather than at end; if an error occurs during testing want to leave container there so can be reviewed for issues.