Modify remaining mentions of biotestmine to be dynamic

intermine_boot is nearly mine-agnostic; we just need to use `_get_mine_name` in two more places:

https://github.com/intermine/intermine_boot/blob/6b155b468381e99c93b374b9043ea1c3a5e409da/intermine_boot/archive.py

https://github.com/intermine/intermine_boot/blob/a3d5fb7fa881d6a5fccbe5c6a5c9baf4804cd526/intermine_boot/commands.py#L36

I recommend moving and renaming `_get_mine_name` to utils.py as `get_mine_name`, since it will no longer be private to that namespace.