Introduce clock job (overloaded cloud_controller_ng)

* There should be only 1 clock per deployment
* Chose to overload cloud_controller_ng job to avoid duplication
* Set ccng.process_group to cloud_controller or clock
  * Former is the default
  * Latter runs only the clock process

[#62482050]

Signed-off-by: Abhijit Hiremagalur <abhi@pivotallabs.com>