Cross-project deploy fails with 500 once the target project has collections #1606

Deploying one project into another (e.g. staging to prod) works the first time, then returns a 500 on every later deploy once the target has collections.

Steps to reproduce

1. Add a collection to the staging project in Lightning
2. openfn project pull <staging-uuid> --alias staging
3. openfn project fetch <prod-uuid> --alias prod (staging stays checked out)
4. openfn project deploy prod --no-checkout --force: succeeds and creates the collections in prod
5. Edit a job, then run the same deploy again: Failed to deploy project: 500

Lightning logs:

** (RuntimeError) you are attempting to change relation :collections of
Lightning.Projects.Project but the `:on_replace` option of this relation
is set to `:raise`.

Cause

For cross-project deploys, merge uses sandbox mode, which takes the local collections as they are instead of passing them through mergeCollections. Collections from resources.yaml are only names, so each deploy sends new ids for collections prod already has, and Lightning rejects them.