[DM] Unify onModeChanged and frameRateOverride callbacks.

In case when we change the mode and frame rate override aligns
with it, we end up sending frame rate override even though it already
aligns with the mode change rate, this causes unnecessary binder
traffic. combining these into one call reduces the binder traffic
and helps with power saving.

Test: atest LocalDisplayAdapterTest
BUG: 399482301
Flag: com.android.graphics.surfaceflinger.flags.unify_refresh_rate_callbacks
Change-Id: Iaa0a417f899b1fb2278693c23ff60cc5478df86d