Rename const to kFrameTimelinesCapacity

From `kFrameTimelinesLength`.

Bug: 270612751
Test: build
Change-Id: I83e61a19254ab4a63479a2004124cfd2c082da35
diff --git a/libs/gui/tests/DisplayEventStructLayout_test.cpp b/libs/gui/tests/DisplayEventStructLayout_test.cpp
index b7b4ab6..3949d70 100644
--- a/libs/gui/tests/DisplayEventStructLayout_test.cpp
+++ b/libs/gui/tests/DisplayEventStructLayout_test.cpp
@@ -45,16 +45,16 @@
     // Also test the offsets of the last frame timeline. A loop is not used because the non-const
     // index cannot be used in static_assert.
     const int lastFrameTimelineOffset = /* Start of array */ 24 +
-            (VsyncEventData::kFrameTimelinesLength - 1) * /* Size of FrameTimeline */ 24;
+            (VsyncEventData::kFrameTimelinesCapacity - 1) * /* Size of FrameTimeline */ 24;
     CHECK_OFFSET(DisplayEventReceiver::Event::VSync,
-                 vsyncData.frameTimelines[VsyncEventData::kFrameTimelinesLength - 1].vsyncId,
+                 vsyncData.frameTimelines[VsyncEventData::kFrameTimelinesCapacity - 1].vsyncId,
                  lastFrameTimelineOffset);
     CHECK_OFFSET(DisplayEventReceiver::Event::VSync,
-                 vsyncData.frameTimelines[VsyncEventData::kFrameTimelinesLength - 1]
+                 vsyncData.frameTimelines[VsyncEventData::kFrameTimelinesCapacity - 1]
                          .deadlineTimestamp,
                  lastFrameTimelineOffset + 8);
     CHECK_OFFSET(DisplayEventReceiver::Event::VSync,
-                 vsyncData.frameTimelines[VsyncEventData::kFrameTimelinesLength - 1]
+                 vsyncData.frameTimelines[VsyncEventData::kFrameTimelinesCapacity - 1]
                          .expectedPresentationTime,
                  lastFrameTimelineOffset + 16);