Tests for Blue Green `DataPlane` rollouts: verify `status.rollout.conditions` during and after rollout

[pmalek]

Blocked by Kong/gateway-operator-archive#986

### Acceptance criteria
- [ ] Add tests for Blue Green `DataPlane` rollouts checking `status.rollout.conditions` are updated accordingly

[pmalek]

This is dependent on the changes that we want to do in #162

[pmalek]

Moving this to Cloud Gateways Phase next as the issue that will introduce the change in conditions - #162 - is already in that milestone.

[github-actions]

This issue has been automatically marked as stale due to 60 days of inactivity. Please update or comment if this is still relevant.

[pmalek]

Assigning tentatively to 2.2.