Description of problem:

As a user, I'd like the ability to set the 'mirror on sync' property globally in a Satellite 6 instance.

As Satellite 6.2 includes the ability to export increment content (via ISS), being able to disable mirror on sync allows the user to not have to keep older exports of content around. They could

• incrementally Export from source satellite
• disable mirror on sync on the destination (which today has to be done per-repo)
• copy & sync only the incremental content.

Currently today if a user wishes to disable 'mirror on sync', it needs to be done on a per-repo level.

This RFE requests the ability to set a default mirror_on_sync_policy, similar to that for download_policy, which allows the user to set a default for newly created repos.