text: Title: Remove the st2resulstracker service from st2ctl and development env
  Body: Mistral was deprecated and removed from the st2 in `v3.3.0` release. However there is a `st2resultstracker` service which is used for polling result from async runner. Mistral was the only async runner which means resultsracker is obsolete and could be disabled.
  
  Team agreed that we should keep the service implementation in st2 codebase if we'll need it in future, but remove service from the associated packaging/startup logic, st2ctl , development env.
  
  This should be easy & fun task, if anyone from @StackStorm/contributors wants to help removing that.