Revert "SF: Introduce VsyncTimeline to VsyncPredictor"

This reverts commit b6c7f880460c81a6ce49ccb3334e2d2e1e020f81.

Reason for revert: Regressions tracked as childs on b/326599221

Change-Id: Ic0f959113a2d434d3b6412c90b58b85e5151e436
diff --git a/services/surfaceflinger/Scheduler/VsyncSchedule.h b/services/surfaceflinger/Scheduler/VsyncSchedule.h
index 881d678..85cd3e7 100644
--- a/services/surfaceflinger/Scheduler/VsyncSchedule.h
+++ b/services/surfaceflinger/Scheduler/VsyncSchedule.h
@@ -81,7 +81,7 @@
     bool addResyncSample(TimePoint timestamp, ftl::Optional<Period> hwcVsyncPeriod);
 
     // TODO(b/185535769): Hide behind API.
-    VsyncTracker& getTracker() const { return *mTracker; }
+    const VsyncTracker& getTracker() const { return *mTracker; }
     VsyncTracker& getTracker() { return *mTracker; }
     VsyncController& getController() { return *mController; }