Low: scheduler: always treat degraded results as success

The OCF standard specifies the meaning of degraded results only for monitor
actions. The intent was that no other action can return such results, but for
robustness, Pacemaker should handle that case.

Previously, remap_operation() treated non-monitor PCMK_OCF_DEGRADED results the
same as an unknown exit status, and non-monitor PCMK_OCF_DEGRADED_PROMOTED
results the same as PCMK_OCF_RUNNING_PROMOTED.

For better consistency with the stated meaning of degraded results, they are
now remapped to their successful equivalents for all actions. As with monitors,
they are still recorded as failed actions for display purposes.