Add `erase_old_redcap_code` function to do just that during upgrade

[pbchase]

Add function, erase_old_redcap_code, to
upgrade.py to erase old REDCap versions from a target directory.

Call this new function with a target directory of env.upload_target_backup_dir

redcap_deployment/upgrade.py

Line 28 in 602cb1d

online()