Fix: sbd-inquisitor: fail startup if pacemaker integration is disabled while SBD_SYNC_RESOURCE_STARTUP is conflicting

And tell user to fix the configuration by either enabling SBD_PACEMAKER
or explicitly disabling SBD_SYNC_RESOURCE_STARTUP. Otherwise startup of
pacemaker would be hanging forever, since pacemaker only knows about
SBD_SYNC_RESOURCE_STARTUP.