Prevent autosync reconcile after rollback

[anjmao]

Summary

Our argo application CRD manifests placed inside git repository which also contains services which we deploy. By default we enabled auto sync policy for both dev and prod environments. I needed to rollback prod environment and auto sync disabled automatically which is expected. But later as new deployment was triggered to that git repository argo synced back argo application CRD and enabled auto sync so broken version was released back to prod.

Proposal

If rollback was performed sync policy could be updated by adding manual: true, eg:

syncPolicy:
    manual: true
    automated:
      prune: true
      selfHeal: true

During reconcile argo would need to check if sync policy is set to manual and skip updating it so user is responsible for enabling automated sync back.

Also it would be great to show sync policy status in argo UI as currently there is no clear indication that rollback was performed and automated sync is stopped until user enables it manually.

[alexef]

this also relates to #8686