SF: Implement leader display promotion/demotion

Remove Scheduler::mRefreshRateSelector by using mLeaderDisplayId to look
up the leader's RefreshRateSelector. Replace setRefreshRateSelector with
setLeaderDisplay. Add logic to demote/promote the leader display (always
the primary display for now) when displays are added/changed/removed.

This fixes a regression where Scheduler::applyPolicy no longer respected
the active display after Ifa1bf23bc991fe60e67dba1cb31077e42fd5396e.

Bug: 255635821
Bug: 241286431
Test: Fold/unfold
Test: dumpsys SurfaceFlinger --scheduler
Change-Id: Ib1e8eacd2cdbf0d798ff7e8bb9c25607972104f5
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 1918913..b51210d 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -464,8 +464,7 @@
               typename Handler = VsyncModulator::VsyncConfigOpt (VsyncModulator::*)(Args...)>
     void modulateVsync(Handler handler, Args... args) {
         if (const auto config = (*mVsyncModulator.*handler)(args...)) {
-            const auto vsyncPeriod = mScheduler->getVsyncPeriodFromRefreshRateSelector();
-            setVsyncConfig(*config, vsyncPeriod);
+            setVsyncConfig(*config, mScheduler->getLeaderVsyncPeriod());
         }
     }
 
@@ -928,7 +927,8 @@
             const sp<compositionengine::DisplaySurface>& displaySurface,
             const sp<IGraphicBufferProducer>& producer) REQUIRES(mStateLock);
     void processDisplayChangesLocked() REQUIRES(mStateLock, kMainThreadContext);
-    void processDisplayRemoved(const wp<IBinder>& displayToken) REQUIRES(mStateLock);
+    void processDisplayRemoved(const wp<IBinder>& displayToken)
+            REQUIRES(mStateLock, kMainThreadContext);
     void processDisplayChanged(const wp<IBinder>& displayToken,
                                const DisplayDeviceState& currentState,
                                const DisplayDeviceState& drawingState)