If a harvest fails to save because of a validation, side effects still happen

[atruskie]

With an invalid mapping:

1. you hit finish
2. state machine started changing
3. sftp connection was deleted
4. password and user removed from model
5. model attempted tbe saved with status: scanning and password: null and username: null
6. model save failed because of the validation
7. connection is still deleted but the other changes were rolled back

Now the harvest can't continue, and the sftp connection is not available even though the model suggests it should be.

Possible solutions:

• recreate the connection on state machine transition failure
• check the connection is open when we think it's open (didn't we already have code for this?)

Kinda: https://github.com/QutEcoacoustics/baw-server/blob/40eb8002c1d10632b132b86b6fa94547ed637945/app/controllers/harvests_controller.rb#L36C14-L36C49 but it shortcuts it because we're less than two weeks