Package update fails on compute node, when yum_update checks for
pacemaker status via systemctl command. Because exit on error (-e)
option has been enabled recently, this issue is happening. Fixing
by, executing the command only on nodes where pacemaker is enabled.
Closes-Bug: #1668266
Change-Id: I2aae4e2fdfec526c835f8967b54e1db3757bca17