qa/common.check: _restore_pmda_install() needs to restart primary pmlogger
qa/common.check: _restore_pmda_install() needs to restart primary pmlogger

From the comment added ...

    Potential problem here if pmcd's PMDA config has changed for
    metrics that the primary pmlogger is logging, then that pmlogger
    may exit and not have been restarted before the QA test bumps
    into either (a) an assumption that the primary pmlogger is
    running (unlikely, as we usually get here as a result an exit
    trap at the end of QA test, or (b) check is running with
    a check.callback that checks if the primary pmlogger is alive
    ... it is (b) this is the real problem.

    Only safe thing to do is to silently force a restart of the
    primary pmlogger.

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