Fix deprecated Javadoc link.

#minor-release

PiperOrigin-RevId: 408269341

library/common/src/main/java/com/google/android/exoplayer2/Player.java

@@ -2119,7 +2119,7 @@ public interface Player {
   /** Returns the index of the period currently being played. */
   int getCurrentPeriodIndex();
 
-  /** @deprecated Use {@link #getCurrentMediaItem()} instead. */
+  /** @deprecated Use {@link #getCurrentMediaItemIndex()} instead. */
   @Deprecated
   int getCurrentWindowIndex();