Fresh checkout of 'jiocloud_master' branch always

Reviewed by: sorenh, rushiagr

* jobs.yaml
  + The 'jiocloud_master' branch might be left in an inconsistent state by the previous run.
    So removed the code that does 'git pull' and...
    if 'jiocloud_master' branch existed, delete it and fetch the latest and...
    do a fresh checkout for every run of the job.