Rename getFocusedStack methods

Rename ActivityStackSupervisor#getFocusedStack() and related to
getTopDisplayFocusedStack() to reflect the current logic executed in
it.

Bug: 111541062
Test: atest com.android.server.am
Change-Id: Ib03abd576ef8283d6df7732a8eebfb745573f2a9
diff --git a/services/core/java/com/android/server/am/ActivityMetricsLogger.java b/services/core/java/com/android/server/am/ActivityMetricsLogger.java
index 62f8c72..d3e3af3 100644
--- a/services/core/java/com/android/server/am/ActivityMetricsLogger.java
+++ b/services/core/java/com/android/server/am/ActivityMetricsLogger.java
@@ -184,7 +184,7 @@
         mLastLogTimeSecs = now;
 
         mWindowState = WINDOW_STATE_INVALID;
-        ActivityStack stack = mSupervisor.getFocusedStack();
+        ActivityStack stack = mSupervisor.getTopDisplayFocusedStack();
         if (stack == null) {
             return;
         }