justfile has incorrect db cleanup

[futurepaul]

          @benthecarman I've been wondering about this command, is it right as the default used is `~/.harbor` ?

Originally posted by @oleonardolima in #97 (comment)

I think the correct behavior is just to rm -f ~/.harbor/signet/harbor.sqlite?

[benthecarman]

the command is just meant for resetting the db for tests, not for running in dev. what we really should do is fix the tests so they all run with their own db instead of a shared one