[ResponseOps] add rollback testing for ResponseOps resources

[pmuellr]

We do not have enough testing of Kibana's "rollback" of saved objects for ResponseOps resources. This hit us with the PT1M issue, which was caused by a rolling update of two Kibanas. Some technical details here: #204395

Ideally we'd have some function and/or jest integration tests which can test this. We would want to specifically test the following:

• single Kibana instance, stopped, rolled back to a "previous version", and then restarted
• multiple Kibana instances, upgrading to a new version; one version performs the upgrades, and running "new version" code, while the existing Kibana is running the "old" code. Arrange for objects to be read/written from both Kibanas

We'd want to test as many saved objects as we can, as well as different connector- and rule- types.

[elasticmachine]

Pinging @elastic/response-ops-cases (Feature:Cases)