Only call onNewVsyncSchedule if the pacesetter changes

When re-calculating the pacesetter display, we may end up with the same
display, and therefore the same VsyncSchedule. In that case, we don't
need to apply the new one.

Bug: 276367387
Test: atest libsurfaceflinger_unittest:SchedulerTest
Change-Id: I76750ffdba6c3d790a98b65aabbc8b13eab3b4ae