Problem statement

JENKINS-54057 added the automated rollback feature, but without yet rolling back the configuration data.

Expected behavior

In case of a rollback to UL-N, configuration data snapshot should also go back to UL-N. As described in https://github.com/jenkinsci/jep/tree/master/jep/302

Additional comments

Testing

NOTE: we need to write a dedicated plugin, or find an existing one, that will fail if rolled back to a previous version without restoring its data, so that we can write a test that will fail if our code does not correctly restore previous snapshot.