qa/common: assorted improvements
qa/common: assorted improvements

- avoid races when installing required PMDAs and/or pmcd options ...
  use systemctl when it is available and/or turn auto restarting off
- detect and remove PMCD_LOCAL=1 setting in /etc/sysconfig/pmcd ...
  QA won't work if pmcd is in "localhost only" mode

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp