For #27700
When uploading bootstrap package for macOS setup experience, validate
that it is a Distribution package since that is required by Apple's
InstallEnterpriseApplication MDM command.
# Checklist for submitter
- [x] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
- [x] Added/updated automated tests
- [x] A detailed QA plan exists on the associated ticket (if it isn't
there, work with the product group's QA engineer to add it)
- [x] Manual QA for all new/changed functionality