Early exhaustion of client-generator for set-delete workloads

The options map in cbjcli provides a default value of 30 for :doc-count, which takes precedence over the :doc-count default of 10000 defined in the set-delete workloads. By default we therefore only perform 30 add operations and 15 delete operations for set-delete workloads. These all occur simultaneously at the start of the workload (since concurrency > 45), causing immediate exhaustion of the client-generator. This particularly affects the set-delete-kill workload, where we then perform those 45 ops before the nemesis ever gets a chance to do anything, breaking the entire puropse of the test.

Even if the :doc-count would correctly default to 10000, we can still easily exhaust the client generator before the nemesis has completed the requested number of cycles. The client generator should therefore be modified to continuously yield operations until the nemesis has completed, in line with the behaviour of the other workloads.