SF: Clean up emitting of mode change event

Clarify the special case of emitting despite the unchanged mode. Rename
functions and state for consistency with DisplayModeRequest::emitEvent.
Remove Cycle parameters for which the argument is always Cycle::Render.

This does not change behavior.

Bug: 255635821
Flag: EXEMPT refactor
Test: SchedulerTest.emitModeChangeEvent
Change-Id: I99debb33ba84dff707d6da0a92dacc4e275fc5ce