CI: Wait for rollout of runners

What does this MR do?

CI: Wait for rollout of runners

Wait for runner rollout to complete after restarting them in the backup spec. This fixes a spec failure where no registered runner is found.

As of runner 0.61.1, runner termination does not take a very long time if the registration has not yet been completed. This causes that the new runners may not have registered by the time the old runners are terminated.

Example failure: #5335 (comment 1768436170)

Related issues

Related to #5340 (comment 1773648626)

Author checklist

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