Further fixes to timer handling under various scenarios

* Fixed the bug where log processing stuck at graph definition when
  table doesn't exit.
* Don't allow state switch from aborted to running
* Counting data fetch from DB, when no more rows fetched and experiment
  completed (aborted or finished), cancel such periodical fetching.
* Don't retry connect to DB after experiment completed.
* Don't retry fetching log, or ec status from OML db after experiment
  completed.

fixes #1626

bob